He is still trying to justify everything by making you the bad guy. He wants it to be "civil" because he doesn't want to make it look like he had anything to do with the action he is choosing to take. I know the emotions are still so raw and hurtful, but you're absolutely right that he uses it as ammo. DON'T LET HIM DO THAT.
Stay strong and if he eggs you on remove yourself from the room and say I can't talk to you about this right now.
Head over to midlife crisis forum and read what I just posted about my H. It will make a lot of sense to you.
Me:49 H:47 S: 16 T:27 M:25 My EA: 2001 His PA: 10/2007, 6/2013 Separated, but H still in house
Find your Shambala: a place of peace and happiness.