I've been around a lot in the past under a different name, so I know a lot about your situation. Don't let the new name fool ya.
Anyway... I'm no expert, never having gone (completely) through a divorce, but it sounds to me like he's .... uh ... jealous. Call me crazy, but it appears to me as if he's jealous of two things: First, he's jealous (perhaps envious) of this new guy in your life. And he's also jealous of YOU. He only wishes that he were as detached from you as you are from him.
He's carrying a torch, IMO. And he's knows he's gonna get burned. It's why he's reacting as he is.
I am not a professional. This is just my opinion...
Me: 44 WAW: 41 3 kids: 16, 12, 6 Married 18 years
EA/PA: Sept06 - Aug08 (?) New guy (suspected): Jan08 - present