I'm having friend trubles!?

I'm mad at person who is an exchange student. He was a friend of mine until my cousins 11, 12, and 13 got on my Face-Book while I was log in, and did the FAQ think that said he was cute and that I would hook up with him. He deleted me as a friend. I asked him why and he said, "Your f-ing stalking me!" He also started a club at the begging of the year to teach the ones who join about his country and laugede. At the begging of the year He was nice to me in school, club and online. Now he is yelling at me in the club and calling my names behind my back. I want to make up with him so we can get on with our lives. My friend asked him to go to a dace with me, but he said, "I'd never go anywhere with that retared."(And I HATE that word) I told him about my cousins but he ignored me completely. I don't know why he is being a complete jurk. I don't know what to do. He'll be gone come June and I want to make up with him at least by then. I don't want him as boyfriend or anything like that, I just want to be his friend or at least a person that he dosen't hate. Please give me your advice.