I hope you can see all these gems for what they are - good advice. Detaching is the ONLY way you're going to get there. If you have to, put a rubber band on your wrist and yank it when you're tempted to engage with him. This man has known you for a long time, and knows full well what buttons he can push.
If you can't wear a rubber band, why not frame him as your most annoying client? I'm pretty sure at work you'd not allow someone to needle you like he does. So treat him like that - engage only on the topics that need to be discussed (the kids) and just leave him be with his emotions.
I truly believe that he's just plain mad YOU pulled the trigger first. My guess is that he never imagined you'd call his bluff and get sick of his crap first. Betrayed? Laughable. As someone told me here a long time ago, stop expecting this cat to bark! (Great visual if you can visualize that.)
You're getting some great advice, and all of it is spot on.
Take care-
Betsey
"There are only 2 ways to live your life. One is as though nothing is a miracle. The other is as though everything is a miracle."
