What should I do about my friend?

I've known this kid since February, I talked to him every single stinking up until about a week ago. I must say I'm a bit oversensitive I will admit. But he said that's all chill. It hadn't bothered him before. But now he isn't talking to me because he says he doesn't want to hurt my feelings anymore. There is obviously more to the story, but he doesn't want to tell me. He says it's too long for him to care to type it. And he won't speak to me via calls anymore. I don't want to drift away. I've asked him if he still wants to be friends and he said yeah. He told me he doesn't want his friends to drift away, but I don't know what I should do anymore. He is depressed, he told me that much. I feel like a terrible friend because I've been so upset about this ordeal that I haven't been very sensitive to his depression. And he won't tell me anything about it anyway. He doesn't talk to me for more than a couple minutes a day. He hardly speaks. He doesn't answer my questions. It feels like he's blowing me off. But he says he still wants to be friends. I don't understand. He won't tell me anything so I can't really understand. I don't know if I should let him be, seeing as he doesn't seem to want to talk to me. Or if I should just check up on him once and a while to make sure he's ok, or continue with my daily text messages (that are cut off soon after a few are sent). The thing is if I tell him I'm going, he won't ever speak to me again, he's quite stubborn. He doesn't talk to me, I incite the conversation. There isn't anything wrong with that, it was like that even when we were on good terms. I'm just scared I'll never talk to him again. He's my best friend. I don't want to say good bye. I don't know if I should leave him alone. I don't know if this is because of depression. I'm worried about him. I don't want to not talk to him anymore. But I just don't know what to do. And I feel hopeless. I'm generally a happy person, I have a lot of energy. But right now I don't have the will to do anything. I don't know what to do anymore. I want it to be fixed.