I think that I'll try doing something that the MC was saying about writing thing down and giving it to the other person. I will tell him that it will not be easy to read, so he can pick his own time to read it & respond when he's had time to think about it. That way I won't be blindsiding him and hopefully will avert him going into fight or flight mode!
I won't push any particular issue (ask him to live up to our agreement about timing of when he moves back in, but I will use it as an example of what I see as a dysfunctional pattern. That way, he can take his own clues, and come to his own conclusions.