I've also found that nice v not nice makes zero difference! I really felt I was the only one managing a situation like this, and it feels comforting to think I'm not. It's so exhausting. Most of the behaviour described really resonates with me.
I've taken a mostly ignore approach for the past 8 years, as I felt afraid of the repercussions. The few times I've taken a stand have resulted in violence on one occasion and furious outbursts the rest. Following the violent incident, we ended up in the family court, which I think he enjoyed. Feeling like he was going to be proven right in court, and enjoying the power it gave him over me when I was clearly an emotional wreck when faced with him. He fought in court for significant contact, but in reality, he takes very little - one overnight a week picking up from school - because of his work commitments. It feels like it was the fight and winning that was most important to him.
This was a few years ago, but still feels painful thinking about it now, particularly in light of the fact that he's broken an agreement now he's overseas with ds (it's politically unstable in the country where they are, and I'd said that unless they stay in the safe part, I wasn't going to let ds go. He agreed just before they left but announced yesterday that they're traveling to the unstable city).
Looking forward, I don't know how to manage this relationship when he is so difficult and has no respect for the agreements we make. On the one hand, I think it's important for ds that he doesn't feel he's in the middle of a tense, unpleasant relationship between ex and I. On the other hand, I've had enough of being nice to him when he suits himself and makes unilateral decisions which potentially negatively affect ds. Nice v not nice, he still feels angry.