Don't take his behavior personally. It probably has less to do with you and way more to do with him. I can relate to this, and I'm sure many others on the forums can, too. A WAS begins to convince themselves that YOU are the problem and the enemy to their happiness, so they treat you like scum. It's so bizarre to see them act so cold & cruel in the midst of your tears even though YOU'RE the one who's being obliterated...and even though they were once so warm & loving...
Seeking's advice is a great one. He's doing what he's doing to lash out at you. If he sees that his nastiness isn't rubbing off onto your positive attitude, maybe he'll get confused and cut it out in the long run.