How do you say no to a guy, that you've wanted for so long?

There is this guy that I liked. I’ve liked her for such a long time. Lately we got really close, and guess he finally decided to start liking me too. Well now I dont like him anymore, he actually disguts me, it makes me sick to think about him. I’ve been rather rude to him when he asks me out and, I feel kind of bad. Other than being rude, whats a way that I can have him know that I dont like him, with out having to talk to him, or be rude to him?