I'm Confused...

I have a problem. I think I like someone who I have known since I was a freshman. He is in my grade and I never thought of him as more than a friend until recently. I get this wierd, bottom of my gut feeling that he likes me too but I don't know. I pick on him and he picks on me but I sometimes get the feeling that it's in a more than friendly way. He's a great guy but I could hurt someone if I was to like him and he was to like me in return. Both of us has changed so much since freshman year and I think that time has definately been on his side. It seems like he went from a nerdy freshman to a confident, great looking senior. I'm not saying that his looks has all the sudden made me look at him in this new found light, but it has helped a little. I have always liked him (as a friend) and never though I was attracted to him but what girl isn't attracted to a handsome guy? I don't know what I should do. I've been thinking about giving him my number but I don't want to hurt my friend. What do I do??