kinda gross....

I'm going to assume that he didn't know the guy was your brother before he started dating you... If he did, then that's kinda sketchy. If he didn't, you can either accept his history is a little closer than you'd like or you can choose to move on. It's an iffy one but I would try and understand.

Everyone has previous relationships you can accept them or not. Knowing that one of those relationships was with your brother for me is kinda weird I feel like there would be a lot of tension between the 3 of you. That doesn’t mean that you 2 should break up though. You, your boyfriend and brother might need to talk with each other this way you guys aren’t uncomfortable when your together. Hope everything works out.

Straight up had this happen to me with my ex girlfriend. Except I didn't know until after my brother found out I had dated her. You're not alone my friend.

You should say, "Bi-bi!"

I'm glad so far no one said 'threesome' in the comments.

Threesome

My brothers girlfriend and I had a thing but I still see her constantly and it's not even awkward... but maybe that's because of the way we left it

Is your brother hot? Still single?