My FI has only one sibling and he and I had an understanding that because his sister was the only sibling either of us had, it would be nice to have her in the wedding party. I agreed that she could be a bridesmaid and both our moms knew about this. I never officially asked her, but I guess word got down through the grapevine because she did end up finding out about it. Which wouldn't have been a problem, but now we're rethinking that decision.
She came to stay with me this weekend, and it was the first time I'd ever met her (my FI's family all lives in the Midwest). It was a horrific weekend. I went out of my way to be really accommodating to her, to make her feel comfortable, and to do things that she wanted to do. She ended up deciding to bring her 2yo son with her, despite not really asking for my permission (I live in a 700sq foot apartment at the moment and its not really equipped for a baby to stay). I tried to make the best of the situation. She was extremely rude for the whole weekend, make backhanded comments about how I'm not going to be as good of a mother as her because I don't want to be a stay at home mom (my FI will be the parent who down-shifts his career when we have kids), how I shouldn't wear so much makeup because her brother doesn't like that (patently false), how I don't really know anything about childcare so I better get a really good nanny (she happens to be a nanny), and a whole host of other nasty things. She also let her kid make a huge mess of my tiny apartment, demanded to be driven around in horrible LA traffic, made me miss a very important appointment due to her lateness, and didn't offer to pay for gas or anything for all of the driving around I was doing to show her the city. The icing on the cake is that she didn't thank me for letting her and her son stay, didn't offer to help clean up, or pay for any meals.
Despite the former plans, FI and I both don't really want to have her in the wedding at this point, because we don't want to have someone who clearly can't support our relationship stand up for us. FI is really reeling from her behavior and is going to talk to FMIL about things, but I can't imagine that much will change. Even if she apologizes, knowing that someone thinks I'm going to be a bad mother does not make me want them to be in my wedding.
So my question is: How do I broach this topic with her? Is there a way to gracefully tell her I've changed my plans? Should I be straight and say that since she clearly doesn't like me, its better for everyone if she just enjoys the wedding as a guest? Or should I stretch the truth and say we've decided to change the way we're doing the wedding party and are going to have it be much smaller or something like that?
(I really want to be a nice person here and I don't want to cause drama or strife with their family. If there's no way to do this without causing World War 3, then I may just grin and bear it and let her be in the wedding, but suggest that maybe she gets ready with her brother instead of me on the morning of or something like that....)
Thanks!