What should I think about this boy?

I think that you should go for it. I mean whats to lose, you already said that you weren't friends with that girl anymore so that's out the window. And with the boy he probably does think that you don't like him but hey if he's into you the way that you suspect he is, he's mind would change as soon as you showed some more interest in him. It's okay to be nervous but don't lose a chance on him if you think that he might possibly be worth it.