Sorry to disappear and cross-post at the same time 
I think I mean that when he says stuff that is designed to get a rise out of you, you pull a vague, 'that's nice, dear' face and look out the window /move on to your next task, but you keep talking to him about ordinary life stuff and answering the civil things he says.
I suppose, that there's a pattern here as Silk - who has a great head for these things - mentions.
The coping mechanism has become these v. long intense crisis meetings where you give him your whole undivided attention for two hours and try to take some of his ridiculous ideas seriously out of a sense of fairness. But that's exhausting, and skews things his way.
What you actually want, I suspect, is a life where there's no need for those crisis moments, and if that's what you want then you have to play a role in cutting out the tension and drama - I totally see that he's introducing all that into the situation, but by noticing and reacting to it is part of the destructive cycle too.
Was the crying just about you leaving then, and not a response to the level of tension between you two? (sorry to be dense)
I'm really not being critical of you here, but I know when we got stuck when DS was small, we sorted it out by each of us drawing those lines in the sand, and then each of us refusing to collaborate in the melodramatic cycle we'd accidentally set up.
Got to run on that note, I'm afraid, as I'm about to be late for a Tidy Towns meeting.
Crispy - I'll be back with the beetroot later.