I'm so confused, and don't know what to do, please help!?

well, there's this guy, well my best friend, and im so confused. he is so lovely to me, and we're very close. when he looks at me its seems to last forever and it's magic. he's always there for me and his hugs are magic because they fix everything. ive known him all my life, and we've always been close, but never went out. and he only lives round the corner. he told me once how convenient it would be if we went out, cos we live so close, and i know his parents, and he knows mine. i love him to pieces, and when i finally told him, he said that he thought it was really cute, and there was no akwardness. he still hugs me, and bullys me just cos he know how to make me laugh, and we just get on so well. i dont know what i would do without him, and all our friends think we are cute together. but now his ex-girlfriend is back in the picture. whenever we talked about her, he has never said anything nice about her, and i honestly thought he hated her, because he tells me everything. after school before half term, he caught me just before i got on the bus, and he gave me a hug, and whispered in my ear to call him more, and that he really wanted to meet up, and then he told me not to miss him too much. im 15, but i love him. but then, 2 days after going back after half term, he asked him ex out, and they're an item. im so confused, and he wont talk to me about it. he isnt being akward, hes being real nice, but i dont get it. i was just starting to think i might have a chance, and i dont know what to do! i thought he hated her, whats going on in his head? His ex, well, now girlfriend is aweful, and im not just sating that because they have been about before. and she is really manippulative and controlling. she hates me, and she knows how close i am to him. i always said that if he went out with anybody, that i would back off, because all i want is for him to be happy, but im really scared that she will try and stop us being friends or something. i dont want to loose him because he means so much, and i really dont know what to do, please help! :(