My twin is really embarsing... Help?!?

I'm a girl and I have a twin that's a boy. We go to the same school and have 3 cles together (btw we're in 8th grade). He's soo annoying. He calls my friends ugly like one of them has gles and he called her a 4 eyed queerr then my other friend is sort of fat not really and he called her a fatazz. I have diabetes and he makes fun of me for having to take my shots. In cl he embares me in front of everyone saying that i sing justin bieber in the shower when i really dont haha >.> Then he spreads a rumor about me how I kissed my older brother and the whole school thinks im ! He spread another rumor about me that i sucked my horse's d!ck (we have horses). Then whenever we go to parties HE comes too and i cant invite friends over without him being annoying and trying to flirt or get with them -__- ugh. How can I tell him to stop or just get away from him?? I already tried telling me to get out of my life but hes like shut up fatty go get stuck in the pantry since your addicted to eating. Should I switch schools since he spreads rumors about me?!