Wow, I didn't realize things still worked that way. That's exactly how it was when I was your age. There was a "leader" and every one in the group liked who they liked and did what they wanted to do. I remember it being very stressful at times. I went to a very small school, so my options were limited as to who I "hung out" with. Having been through that situation, I can now say, as an adult, I wouldn't be friends with her AT ALL. But then there's the issue of all the other girls following her and being mean to you too.
I don't know if you'd be able to do this, but try it. If she says she's not going to be your friend anymore just tell her it makes you sad she chooses to do that. But don't let her know it's bothering you. Like you said before, she'll get over it in a couple of days. And if she doesn't....then I think it's time to find a new set of friends. I know that's easier said than done. Like I said, I've been in your shoes before. I'm sorry you are going through this. Good luck!