He is so far broken its time to get out the broom and simply sweep the pieces away. He clearly has no idea how much he needs help.
I have a feeling his little miss OW tells him all sorts of things to make him feel better about how she is the only one who understands him. Honesty. I think the only thing holding him from leaving is his pride. Everyone will think its his fault. He already told you that.
BBJ, find yourself a good IC. Just someone to be there for you. Let him go.
He is drowning. You tried to throw him a rope, a life preserver and even a boat. You did everything.