I don't know what to do anymore?

so i started off my year with like 3 "friends" we were sort of close i guess, and then all of a sudden they start nagging me about my hair and make up, so i get annoyed but it's like whatever, then all of a sudden 2 of my friends start saying stuff like "oh your so fat, go on a freaking diet" and they kept on saying it, (i'm not fat btw im actually 90 pounds at 16) but they are well aware i just got over anorexia and i don't know when it will return, so that seriously got me mad, then my last friend decided she was gonna spread rumors about me, I have no idea what to do any more, all i want is a good friend, and in a private school there isn't that many options, any ideas? please please help