Originally Posted by
TxCat
I agree with the above.
As an aside, OP, I can sympathize with your situation pretty well. The biggest fights in my marriage have been about DH's family, specifically his brother, who has been super rude, disrespectful, or passive-aggressive to me in the past. I actually thought at one point in our first year of marriage that we would separate because of it, in large part because DH just didn't seem to acknowledge my point of view at all, didn't recognize in any way how inappropriately his brother was behaving, and just wasn't supportive. It was very damaging to our early months of marriage. We've worked through a lot of that, but it was hard. The upshot is that DH and I are more on the same page about these things (he recognizes his brother's bad behavior finally), but his brother still behaves badly so we still have to work through these situations pretty regularly, and it obviously is a source of great stress for DH (he'd much prefer that everyone get along, for obvious reasons).
My advice - go to the party, but not have a big talk with SIL right now. Why do you need to have a big talk with SIL? Why is that necessary before going to this birthday party? Sure, your whole family going might feel like you're just putting on a show of sorts, but isn't that true with a lot of adult life? Don't we all do some things, like faking a good attitude in certain situations, because it's sort of socially expected? So I would go, and if SIL or your DH really think that you need to have some big conversation, suggest that it would be better suited to after MIL's birthday party. And if you go, I'd just concentrate on hanging out with your kids if you need an escape from interacting with the rest of the family.
Finally, I'd suggest not focusing on how you think SIL is possibly manipulating the situation, i.e., wanting to talk now before the party, why now, why on "her" timeframe, etc. If the family, or MIL, wants to have this 80th birthday celebration, I think it does seem natural that they are then also figuring out the how's and if's of your family attending, since there have been problems there. Your SIL might very well be passive-aggressive and manipulative, but I do think that this seems like a natural time and reaction to trying to improve relations, even if it's only temporary for this one event. If she thinks it's a "win" for her that she's forcing you to attend or talk, that's her problem, not yours. You can't control how she is viewing things, you can only control your behavior. I've found that I feel much better about my IL situation once I started actively trying to take myself out of the petty mind games and tit-for-tat business, and tried to be much more straightforward and polite - I'll attend these family events, but I refuse to let myself get sucked back into the drama. If BIL starts behaving badly, that is a reflection on him (a 41 year old who acts like a 12 year old), not me, and it's not my problem.