My friend is like head over heels for her boyfriend and he likes me, what do i do?

K, so heres the deal: My friend lost her virginity to this guy. She is crazy about him, and it looks like he is for her too. However, another friend of mine is always saying that i am so compatible with this guy, and she asked him if he would date me. He said he would, and though i am flattered (and i am disgusted with myself for being so), i feel exceedingly guilty as she is my friend. I dont really even look at him that way, plus I can't date until next year, and he is kind of waiting. What do I do? I am afraid to tell her, but i feel so guilty, she has given him so much.