How to get a guy that knows I like him to like me back?

ok so here's the deal. I've liked this guy since January. Were just acquaintances and we've had a few classes together since freshman year. He's really sweet and really cute. Anyways in about March or April I asked my friend, that had a class with him, to tell him that I liked him. She, being the best friend that she, is obliged even though it was very awkward for her lol. Anyways she told him and he didn't respond negatively he just said alright I know who it is. Since she didn't actually say my name( she told him that she had a friend who likes him, he asked if we were best friends, she said yes, etc etc) by the way, there is no way that he doesn't know its me because everyone knows that my friend and I are bffls and she gave him other clues before that too. Well all the time after that I've been hesitant to talk to him in classes or even look at him because its just a little weird that he knows. He's always so polite though, he never blows me off or treats me any differently and that's part of the problem:(. I don't know what to do. Every time I talk to him my voice gets all fake high pitched and I get shy and he is, as always, really polite but doesn't act at all the way he does around his friends . I kind of want to get over him but then he wrote in my yrbk that he wished we had more classes toghether and that he regrets not getting to hang out at all and that I seem like a chill person and that he hopes we see eachother more often next year. Its soo sweet but its probably just yr book talk. That probably why he said "next year" instead of the summer. What should I do? oh and were both in high school and were going to be seniors next year.Thanks for listening:)