and I think it's messed up, but wanted to at least see if he was willing to let it work both ways. Then I would know if I was dealing with a genuine belief...

I'd just refuse to play along with that crap. But that's me.

How do you talk openly and honestly about what your needs are without giving H the power to use it against you if he so chooses?

By not letting him have that power, that is, by being detached so that any attempts by him to trigger you deflect off you as if you were teflon coated steel. Think of it as being the antidote. Now his poison doesn't work on you anymore, and he's powerless.

My lawyer thinks H is setting himself up to be seen as the "primary caregiver" for a custody case.

Well if he truly is, good luck to him. I don't see it happening, because you're going to play the 'unhappy wife who has the disturbed controlling abusive husband who locks people in the laundry room and refuses to go to a marriage counselor and puts the children in the middle of this' card. Hope H has plenty of money for the attorney fees he's going to needlessly and futilely run up. And from what you reported, the attornies apparently hope so too.

but I have to get there mentally to be prepared to do it.

'Fraid so. I'm not one to advocate a breakup, OK, but not all relationships are worth saving. And boy, Heather, if you can get to that place where you can walk without looking back, that will put you soooo much in control of the relationship - and your life.