Friend trouble. Please help?

Okay so I had two BFFs. We all treated each other equally for about five months. Then one of them (lets call her Jenna) started getting real buddy-buddy with the other one (lets call her Kiara). Then they both ditched me, turned the school against me, none of the girls were talking me, they discluded me out of everything. I cried so much, I lost weight, I was really depressed. Now when we finally started to get a little closer, she goes and tells this girl that I always insult her behind her back and then she gets really mad at me. I try and deny it but she listens to Jenna since Jenna is really popular and has a big difference. Now she is one by one turning everybody against me and I don't know why!!! I can NOT talk to Jenna because she will only take advantage of my vulnerability. Now nobody likes me, I wander around at recess and lunch, avoiding anybody I know. Sometimes I sit in the washroom and read a book to avoid the mean eyes that follow me everywhere I go. I cannot tell the teacher because what can he do? Tell them to be my friend or else? That would make me sound really weak. Everybody moves away when I sit near them and now I'm so depressed and lonely. Even if my teacher tells them to be friends with me, it won't be real because she will still give me those looks and I'm so sad. PLEASE HELP????