I'm isolated...I have no friends now?? What should I do??? Why is she acting like this?

You just said the reason she's jealous of you she can't stand the fact that you do better then her. I'm sure you can move on to another group of friends that's what I do when I lose a few friends or a whole group I move on. I just randomly start conversation with some people usually my aquantices you know those people who just says hi and bye in the halls (sorry if I spelled a couple of words wrong) lol....remember there no matter how nice u are there is always going to be some one who doesn't like u and that's ok forget about them and pretend they don't exist go and talk to people who are worth it