I consider this to be partially my fault but here's the deal:
Almost a year ago, some friends and I were hanging out. My now fiance and I had just had the marriage talk (EDIT: as in we both wanted to get married and saw it in our future) so the group was abuzz with hypothetical wedding planning. I had listed off a few people I thought might be in my wedding party. She was one of the potentials on that list.
Fast forward to today:
I have seen this person twice in the past year (her mother's funeral and a game night at our apartment) and have only had a conversation with them on two other occasion through text - once when her dog ran away and when she told me her mother had passed away. I know she'd had a rough year but I feel we've drifted apart. I'm moving to another country this summer for my PhD and will be having to planning my wedding from a distance.
Because we are moving and have recently gotten engaged we wanted to throw a party to see everyone. I sent her an invite on Facebook along with a dozen or so other people. She texted my roommate about the party and said that she was busy that day but she was trying to rework her schedule because she feels obligated to go since she's in the wedding party. She texted me this morning to say that shes coming.
The party is tomorrow. What should I do?
My fiance and I have discussed the wedding party a bit and we both agreed that she won't be in it, as she has been distant, inconsistent in supporting our relationship, and has slept with one of my fiance's best friends (he thought it was casual; she didn't - there's major awkwardness between them). Besides we want to keep the number of BMs & GMs equal, and he's struggling to come up with 5 (the current number on my list: my 4 closest friends and his sister).
Clarifications:
-I was not engaged when my friends & I were talking hypotheticals
-I don't care who she has sex with as long as she doesn't get upset with me for other people's actions and relationships (which she did get upset).
-She has been unsupportive in the sense of questioning if we were right for each other & thinking we were moving too fast/telling us how we should handle our relationship.