He is upset because you took him at his word! You didn't beg, plead, or continue being his sex bunny. Instead, you took him at his word, and you continued on with your life. He isn't used to women who listen to his words and believe them.

It might be a very good idea, for your heart's sake, to consider why you're still having conversation with him. Because you want to be friends? Who wants to be friends with a sleep-about? Who needs friends like that? The more you talk and try to reason with him, the more chances he has of getting into your pants again, and the greater chance that you will develop an attachment to him. He has everything to gain here, as long as you're still engaging with him.

Set him free. Let him find that girl who wants to have sex whenever he says so, and yet have no commitment, because I think nothing short of a miracle is going to settle this one down. I've met too many of these before, and seen this one too many times.

Set the little fishy free and find one who isn't afraid of being committed to you and only you. You are worth it.