What do I do with a cousin whom I really cant stand?

Ok, she is 13, and i am 14. She is not really the most attractive (no offense, this is not just cos i dont like her) she is ok, maybe like a 5. But she has A TON of boyfriends, and always is telling me about them. I think she does it to make me jealous, since i've never had a boyfriend. Then, when i was in town (where she lives) for like 2 weeks, she made up stuff about doing lots of things with guys (yes, THAT stuff) and she is just manipulative, a liar, and vindictive. What do i do? we dont see her very often anymore, but stil. I always get agiatated around her, and dont know what to do anymore....please help me, thanks sooo much :)