If you apologise he'll start following you again. Do you want that?
Just tell him the truth, tell him exactly how you feel. Apologize first, and then explain, I'm sure thats your best bet.
Tell me what you said to him via PM, and I can help you out from there.
He may forgive you, but he will never forget what you say. This is one of those moments in life when you learn a lesson the hard way. :p Just be persistent and keep trying to apologies. Be sincere about it too, people know when you're just bsing an apology. Good luck.