So my fiancée hasn't formally asked him yet but I'm not happy with his choice of best man. I'm okay with him being a groomsman because it's his friend and I understand that. But I don't get why he should be the best man if he doesn't support our relationship. He's told my fiancée multiple times in the past to break up with me and doesn't support us being together. It upsets me and causes me anxiety for him to even be in the wedding but it's my fiancée day too. I don't won't to be controlling but I'm not okay with him being the best man. What do I do?
Unfortunately there isn't really anything you can do. Why your fiance would want to remain such good friends with someone who obviously doesn't like you nor supports your relationship I have no clue. But it's ultimately his choice who he picks as best man. It's unfortunate he can't pick someone who actually supports both of you as a couple.
Yeah I agree with what the person above me said. You can share your feelings with your partner and talk through it, but chances are he's going to stick with the best man he chose. There's a reason he chose that person just as there's a reason you chose your bridesmaids. Maybe if you talk it through and he hears your concerns it may be enough but only your fiancée can make the final call ya know?