You are much better off without him. My 3y/o daughter has better social skills than your friend. If he was truly your friend, he would have told you what was wrong before de-friending you.
So the only reason was that you were dating someone new? Maybe he has feelings for you?
Yea I'm gonna definitely guess that he had feelings for you and he immaturely handled them by just cutting you out of his life. It sucks, but seriously he sounds like drama you don't need.
The man lacks social skills. I've seen 8th graders handle a friend situation with more class. You need a friend who has your back, not someone stuck in middle school.