puppy - regarding his STUFF being sent back and forth - essentially, try and add this as fuel to your fire. The fire that you are going to burn him with. Not literally, but legally. What he has done is just another incident of abusive behaviour - he's trying to control and undermine you, run rings round you, provoke you. I would suggest you stay strong and do just what he wants but make sure it's all recorded. He wants you to fight and battle, say "no I won't have it your way" - when you do that he has drawn you in again. It's the disengaging thing that you know all about, but perhaps can't see it in perspective here as it's kind of drawn out over time.
mo - selective hearing, selective memory... Perhaps they are natural symptoms of being an abusive person. Perhaps they genuinely can't hear or can't remember because for so long they have been blocking stuff out that comes from you, because it's not about THEM. Narcissistic stuff. But I would agree you are going down the right track to have other people witness things, do put him on the spot in this way.
I remember about 15 years ago, leaving my OH, my friend going over to tell him and he said 'I thought you just wanted to move out, not end the relationship'. I believed that he didn't understand. Naive me just went along with it and accepted this feeble excuse. How soft am I.