I haven't read any of this thread except the first page, so here's my advice:
Contact your teachers. They will ALWAYS offer support and help whenever you need it, as it is their job to do so, don't bother making threads on forums. Asking people around your age will not help, just pluck up the courage to speak to these people, or just get your parents to do so. All you need is their phone number or email address. Once they see that you truly care about your education then they will be more than willing to offer help.
Secondly,
To all of you people here telling this girl is a horrible person because she bullied someone, you're f***ing pathetic. You should be EDUCATING this girl and making it clear and aware of what was wrong, not doing the same thing she did to the person she was mean to. Calling her a "****ty person" and stuff like that isn't going to make her stop bullying other people. Do you honestly expect a person to change when you personally attack them? No. People don't work like that.
Jesus christ, some of you guys here are a lot older than her, and you're supposed to be setting an example. Not reflecting her behaviour. Grow up.