Wedding Stress. I need SERIOUS advice

My fiancé and I are getting married in August. We will be tying the knot on our 6th year anniversary, so as you can imagine I've had a lot of time to get to know all of his friends and family. Recently, his best friend started dating this girl who I've been very vocal about not liking since the very day that I met her about 5 years ago. I'm not an argumentative or dramatic person, but I'm also not very forgiving at all. I get along well with literally everyone else except her, because she's been very rude to me since day 1. Ive only even been around her a handful of times, but every single time she's done something that rubbed me the wrong way. Now that we're getting married, it's time to put together a solid guest list, and it's a no brainer to me that she's not invited. That never would have ever been a problem EXCEPT for the fact that she's dating my fiance's best friend now. So his best friend is butt hurt about it and has pretty much gotten my fiance's entire family to also be upset with me about not allowing her to attend our wedding, even though they all knew about my problem with her years before they were dating. Now my fiancé and I are in turmoil because he feels that the pressure is on him. My question is WHAT DO I DO? Am I wrong for not inviting her? I've told my fiancé that he can call off the wedding if he'd like, because there's no way I'm budging on this. I don't feel that I'm wrong, but I am definitely stressed. What would you do??
I'll also add that this back and forth has been going on for months and I think it's really weird and messy that she would even want to come to any event where she's not wanted.