I'm not sure how long this is going to take.
L1: LW1 is in a slightly worse position than that occupied by Elspeth Scallon, who becomes Sister (later Dame) Cecily in In This House of Brede. Elspeth's mother digs in her heels and does all she can to prevent her daughter entering a Benedictine monastery, but does not quite go to such lengths as setting up fake appointments. Mrs Scallon is by far the driving force in her household, with a quiet husband who tends to give in and let her have everything her way. But Major Scallon (whose main mistake, if we recall Lady Elliot and perhaps Mr Weston, might have been in marrying a St Clair, who regarded his family as middle class and hers as good) is quietly supportive of his daughter, whereas F1 clearly lines up behind M1 and supports M1 even behind her back.
In cases with an outrageous parent, it's difficult for even the Prudecutor to gang far agley, as Rabbie Burns might have put it. All things considered, LW1 is doing rather better than all her friends who are driving themselves into anorexia or various other disorders. She appears to have taken for her role model the estimable Wendy Crump, the only person not put out when Claude Erskine Brown called her fat.
As for what LW1 can do, she can certainly try to establish ground rules with M1 - not much chance of success. If she's very lucky, she might manipulate M1 into going too far for even F1 to take - if F1 isn't really on M1's side all along and likely to become more open about it. She can find a new counselor, perhaps even having one or more joint sessions with M1 (likely if it can be presented to M1 as the fastest road to get LW1 to agree to surgery). Or LW1 can just find some way to avoid going home for the summer - probably the best option, which has the potential side benefit of nudging F1 into realizing that M1 has driven LW1 away if he really is on the fence.
L2: I like this letter because it is easy to brief oneself for almost any side except that of the LW (and, of course, the Prudecutor). Taking this point by point:
Separation/divorce devastated H2 when he was about 30 - This does not seem inherently to favour either parent. It might be used to suggest that the marriage was a happy one and the reason for cheating frivolous, that H2 was much closer to P2s than usual and that that and not F2's conduct caused H2 to take a side, or that M2 was good at applying band-aids.
Learned that M2 was cheating with a married man before the divorce - Learned from whom? I suspect that this is the key to whole situation. It's quite plausible that F2 was only too eager to punish M2 by broadcasting her infidelity. It's quite plausible that M2 was only too happy to justify her cheating by claiming that F2 drove her to it. It's plausible that a partisan for either side made the big reveal. This is a bit of a toss-up. It seems slightly more likely that the wronged party would have fewer disincentives to raise the issue, but that can be balanced by CP2 being married himself. This is a point that the Prudecutor overlooks. One can conjure sympathy for a married person who cheats under particular circumstances. One can conjure sympathy for someone cheating with a married partner, perhaps a little less easily. But a married person cheating with another married person is exponentially more likely to bear the brunt of the blame. It is a bit like believing that both Mrs Rogers and Antony Marsdon committed suicide in And Then There Were None.
Devastated F2 relied heavily on H2 for support - Again, what kind of support? Was F2 spending week after week picking over the carcass of M2's conduct? Or was he unable to get through many of the various necessities of daily life? There does seem to be a slight double standard favouring women in terms of a stricken spouse spiraling into depression - but then there is a contrary double standard favouring men in terms of speedily entering a new relationship.
Heavy toll on F2 - Again, could be spun either way. F2 was filling his ears with all of M2's misconduct and forcing him to choose between them. F2 could barely function and it killed H2 to see his father so incapacitated. Take your choice.
M2 living it up at parties with boyfriend - LW2 begins to go off the rail here. Yes, it can seem a bit unpleasant when any relationship ends if one partner, who left for another relationship, is out and about with that partner, but one may recall that Evgeny Platov and Maya Usova got more than just their own back on Alexander Zhulin and Oksana Grischuk. It may be unusual that CP2 should be equally free at the same time (and it would have been nice if LW2 had mentioned how that relationship has resolved itself if at all). This shows that LW2 is clearly taking F2's side, despite F2 having been in effect more closely related to the toll taken on H2. But that doesn't necessarily advance either side inherently.
Wounds healing, loving relationship restored between H2/M2 - How is F2 reacting to this?
Good relationship, but lost so much respect - Did H2 lose respect for M2 as well before the difficulties of F2? While H2 might not have been much up on what happened in the few years leading up to the separation and divorce, he'd know a good deal more than LW2 about how the marriage had been for many years - not that he would necessarily have been right, but he'd have a much better idea about it than she.
How to carry on with internal bitterness - Is LW2 serious? That's the whole point of "family" gatherings in the first place.
Happy ending/pressure - While the pressure is plausible to assume, we have no particular evidence that F2 ever pressured H2 into blaming M2.
Confidant - Assuming facts not in evidence.
Most importantly - The Prudecutor cannot know that H2 felt he had to take F2's side. Plenty of adult children of divorce pick a side without any prompting whatsoever. Here the prompting is plausible, but not conclusive, and there are equally plausible theories in the works.
Messy/painful/silly - Sounds as if someone is describing her own extramarital adventures, but I shan't go there...
Cordial/enjoying her company - Civility is entirely enough; cordiality will come as it can. There is no point in straining, though there are ways to arrange time spent together to be more likely to be as pleasant as possible, anywhere on a scale to suit LW2's instinct of how pleasant she wants to be.
Probably devoted/lucky to have her - There is NO FOUNDATION WHATSOEVER for assuming that M2 will probably be a devoted granny. All we know to be probable is that she has less than the usual amount of regard for the married state.
Points of interest: F2 seems to have faded from LW2's consciousness. How he fits into H2's repaired relationship with M2 (or not) would have been interesting to know. And again, I shall return to the point of who spilled the beans about the affair in the first place.
As for what to do - it's impossible to care. They all sound like rather unpleasant people.
L3: Divorce sooner rather than later. H3 is clearly more involved in maintaining some sort of parity with XW3 than he is in having a trustful relationship with LW3. And for pity's sake don't keep reproducing. Yes, XW3 sounds like a real piece of work, but my sympathy for LW3 is extremely limited, as this was, like a game of chess, an open problem at the time of the marriage.
L4: While I rarely call Fake!, here I have one of my favourite reasons for doing so - Dr Schwyzer.
One of the interesting tempests of the recent past involved the uproar surrounding Dr Schwyzer after a fairly banal interview of him by one of his friends and admirers was posted to one of the better-known feminist blogs. Comments were not running especially strongly in either direction until an anti-Schwyzer faction began to coalesce around the resurfacing of an old blog post of his in which he responded to a friend's sense of guilt at having let his dog outside to face foreseeable danger from coyotes with an account of the time he'd attempted to commit a rather white-knighty murder-suicide during a time when he was far from sober and an ex-girlfriend in dire circumstances popped back into his life.
Matters were not greatly helped when the interviewer, claiming private health concerns and lack of productivity, closed the original thread. She then posted shortly afterwards a somewhat preachy piece about redemption and forgiveness with commenting disabled. The fun began when the site's main poster started a new thread, basically stating that the original interview might have been better left unposted, there were problems with Dr Schwyzer's participation in the feminist movement, and that, despite those problems, an outright ban was not quite her version of the ideal response. (Not that he ever posted there again, but a pre-emptive ban would have been unprecedented.)
During the over-thousand-post thread that followed, one of the pursuits of some posters was to examine other writings of Dr Schwyzer. He had not long before then caused a bit of controversy by a series of posts dealing with his having some years previously acceded to the plan of a sex partner of his, who decided to marry her other sex partner after becoming pregnant, not to inform the other partner that she hadn't been exclusive at the time of conception. While this post did not raise much ire in light of the newer scandal, other side lines included his outing his second ex-wife as a lesbian.
But the point of this post and my cry of Fake! springs from the best of reasons. Someone found another post of his from about 2007 in which he'd related a source of considerable distress. He and his wife were about to give a large party, and, at the last party they'd given, most of the guests had overridden the assigned seating Dr and Mrs had so lovingly arranged for their benefit and swapped out their place cards to sit next to their loved ones. And therein lies the rub. For one thing, people who use place cards almost never sit husbands and wives next to each other. For another, what sort of moron trying to poison a DIL would risk putting her own son next to her?
As far as the merits of L4 go, LW4 was either incredibly hostile, incredibly feckless, or both. Change condiments with her husband's without telling him? What if, after all the previous instances of poisoning had passed off without anyone but the victim being suspicious, MIL4 had finally decided to go the whole hog and poison LW4 fatally? And, at the very least, she admitted to H4 that she deliberately gave him doctored food that made him ill, being of the opinion that it was highly likely to do so. Who on earth would stay married to anyone who did such a thing?
This one is a no-brainer. This couple has not earned the privilege of divorce and should be forced by order of the state to remain wedded in perpetuity. Family meals will end up looking like the famous dinner scene in the video game version of Clue, when Mr Boddy's will has been read and discovered to be of the tontine variety, with the last survivor to collect all the boodle. Fun times.
Moral: "I think Kitten should try."