How to deal with your bf's ex gf....?

I've been dating, well engaged now,to this amazing guy for about two years now and he use to date this girl, that I'll call Susan, before me. They weren't serious just fooled around I guess you could say. When me and my fiance first got together, I heard a lot of things about her from his friends and family. One night, we all decided to go to this bar and she was there that same night. No surprise though bc this was one of her hangouts. I'm not the type of person to get pissed off at my current boyfriend's ex because they did me no wrong but this one in-particular I do not like ONLY because as I was walking out of the bathroom at this bar, she was coming in and I tried to hold the door open for her being nice and she bluntly said, "I know how to open my own door". Therefore, I closed the door and made her open it herself. Every since this incident she's been a total ****** to me. It would be easy to just ignore her and pay her no mind when she's not in our lives but most of her friends are friends/family of ours. Seems like no matter where we go to hang out with our friends/family she always seems to show up and ruin my night. To make a long story short, how do I get over the fact that she's a ***** and tries to rub the fact she was with my man in my face?