Well….if he doesn’t even acknowledge you when you’re in the same room, there’s really not much of a relationship going on. Given that he’s showing you a cold shoulder since he told you he wants a romantic relationship with you, I wouldn’t put too much stock in the outcome.
I think it would be wise for you to consider him a friend who likes you a lot, but probably would not be great boyfriend material. If he’s blown the friendship by exposing his feelings, and he isn’t able to recover the friendship, then that’s the outcome for now. He’s probably embarrassed over showing his vulnerability, not being sure of your feelings, perhaps changing his mind, or realizing he doesn’t want to be more than friends, or some other reason. Regardless, the best thing to do now is give the friendship some space to recover if that’s possible.
My guess is that if you show him a “soft landing pad” by being the friend you’ve always been for him, then eventually, he’ll pull himself together and be able to be your friend again. But there’s always the possibility that he’s so sensitive that once he’s crossed the bridge of telling you his deeper feelings for you, he can’t swim back to the way things were.