How do I deal with a mean cousin?

Alright, so I have this cousin who is okay and everything, but she is so mean to me. She'll be nice for awhile and then she'll get tired of it or something I guess. She used to live in the upper peninsula of Michigan, and I live in the lower peninsula, so I never had to see her that often. Usually it would only be during the summer every other weekend when I visit my dad. She moved to the same town I live in though, and next year she's going to go to the same school I go to. I can barely stand her for half an hour, let alone seven. Her locker is going to be right next to mine too. And she's expecting to hang out with all my friends because all of hers live eight hours away. She just says really rude stuff to me, like "It's too bad that you didn't get the skinny genes of the family like I did." Whenever she says something like this I get so mad. I'm 4'11" and 105 pounds. Not exactly fat. And where I am all muscle, she has tons of cellulite. Gah! She just makes me so mad! I just have a really bad feeling that she's going to steal all of my friends and be rude to me all of the next two school years. I'm getting sick of being a doormat to her. What can I do to stop her bullying?