Griffe my friend.....
He asked for honesty...you gave him what he asked for. If he is not man enough to take what he asks for, there is nothing you need to apologize about. He is responsible for his actions/reactions. So what if he's pissed off right now? Maybe he's more pissed off that you are right in your honesty and he's having a difficult time accepting that about himself. Maybe he's projecting on to you his dislike of himself.
You've apologized for hurting his feelings....you do not need to continue apologizing. As a friend, you gave him what he asked for. Now it's up to him to decide what to do with that information. You cannot control how he reacts to it. If I were you, I would back off, stop apologizing and let him be to figure out in his own head what he needs to do and how he is feeling.
Hold your head high and know you were a good friend to him even if he can't see that....it's his loss.

sabby