Is there any suggestions,how can i move on?

A few months ago..I was friends with this girl..While i was friends with her..I started to fade away from all my other friends,I'm in grade seven,and were both 13,But while i was friends with her, a lot of more people started to hate and hate me... my only friend started to be her... It was sad. Because i was one of the most populars in the school, i was so nice. I still am. It was a clique. Me katie and sarah... Katie made me and sarah feel bad all the time and try to make us whores. Katie does alot of things with guys, And me and Sarah aren't ready for that.... me and sarah decided to just move on and try to get our friends back, But now that were not all friends, I'm sooo much happier. It;s just were in the same class... And she trys to make me jealous now, But she hangs out with the losers... Any help?