He wants what he can't have. He is letting his selfishness and pride make this decision. Why change his mind all of a sudden?
Imo, he is no good if he is going to do that to his friend. That should tell you a lot about him in general. Sorry to say this, but most likely, he is working on the fact that you had a thing for him in the past. Maybe, he is just trying to prove a point for whatever reasons
Beside this point...Why are you even listening to this guy in the first place? Does your bf know about this?
Anyways, I don't know if he is genuinely into you or not, but from the information given to me by you in this post, he might be just playing with your emotions or whatnot.
If you didn't tell your bf about this...You should and quick. He has the right to know, and if you don't, you are just as wrong as this clown of a guy. Guys like this make me sick, and they deserve a slap upside their head or worse.