My fiance and I met through mutual friends. At the time we met and got engaged, our mutual friends were a couple. They're recently going through a VERY nasty split. My fiance and I are both trying to be there for our friends, offering moral support and helping out with their daughter's birthday party since they were both laid off recently, but it seems as though they are using our wedding to air out some of their drama. She is my MoH and he is a groomsmen. She recently expressed that she would like to bring another date, and I said, yes of course, and asked if her ex would be able to be civil if she did. She said she didn't think so, so I had my fiance talk to him, because we didn't want him getting angry or not enjoying the day because she randomly had a date. She then got angry at us for giving him a heads up. It just seemed like she wanted to make him mad/jealous and thought our wedding would be the best place to do that. I know I can't control their behavior, but does anyone have any suggestions on how to deal with this kind of conflict, or had anything similar happen? They both mean the world to us and I don't want what should be a happy day for everyone, them too, tainted by drama.