Angry Rant of the Ages

I am mad. Now that we've established that I should be able to move on but seriously! A couple of years ago there was this girl my friends and I knew by relation (she was friends with some of our friends). Our friend group was small, exclusive kind of and she had ditched her only friend to be a part of it. The problem was, we had nothing in common! NOTHING! Our sense of humors, our interests, our social habits. And I hate to sat this had anything to do with it, but no one else that knew she existed really liked her. So, we ditched her. Plain and simple stopped talking to her, stopped hanging with her, ditched her. Part of me felt it was karma since she did ditch her friend to be friends with people she thought were cooler. Was I wrong? Yes. Do I feel bad? Yes. Did I apologize a thousand times? Yes. It's been two years and everyone involved and/or friends with me and the girl agree we were young and stupid and it's over and done with. But the girl, who I thought was over it as well because we have been on neutral terms for about a year now just dug it up! Publicly.
In our shared class (unfortunately we have one this year) the teacher asked for interesting things about us on a note card. After about a million answers like 'my favorite color is blue' he read one off that went like this "I pierced my own ears in 7th grade and then went on to pierce Katherine Davis's ears three months later. She had a very low tolerance for pain which might be the reason she and her friends ostracized me all of 8th grade." This hapened TWO years ago. And it was mean but it wasn't public! At the time I very well could have told everyone her secrets or shouted about how much of a loser she was and the things she had done but I didn't. We kept it between us, I never repeated a moment of her life to anyone. So why does she feel the need to do that to me? She has friends, I have other friends it's all over. I for one just want to forget about it.