I don't think any of us can tell you what to do. You need to decide that for yourself.
I think that even though you thought he wouldn't attend, when you put that offer (invitation) out there you need to accept the possibilty that whoever it is may actually come. I can understand why you wouldn't want him there, but if you truly had absolutely no desire for him to attend, you wouldn't have given him a STD... pressure from sisters or not.
Because you haven't heard directly from him that he is coming, as of right now it's all rumor. You can either call him yourself and express your feelings to him about his possible presence at the wedding, or you can let the anxiety of it all get to you (which would probably make things worse).
You stated the worst that can happen in your eyes... that he will bash you at the wedding. But the best that can happen is that he doesn't bash you and instead respects that this is your wedding day and attempts to repair your relationship. But until you talk to him directly the anxiety of "what if" is going to be there.
Good luck! I hope it all works out.