I will answer my own question about detaching. At times, when H gets crazy and irrational, I have this overwhelming thought in my head to run away and give up on him, if he can believe xyz there is no hope because he is just so out of touch with reality. This has happened at least 1-2x per week since BD, and if I am honest, for the several months leading to BD. Usually he is ranting and emotional, and just spewing rage and hateful things at me. And then a little voice inside my head tells me to STFU and I do. And I validate and I reassure - usually apologize for something, say I understand this upsets you, I am sorry I didn't fully understand before how much this bothers you, I get it now, - that type of thing and it works. H calms down and our marriage is still intact.
The problem for me is the little things- when H seems calm or when my anxiety is building. Then I don't detach. But when he is losing it I am able to. So I need to remind myself that it is the same thing. And when it is a "little thing" and I am tempted to react, I need to remind myself that it will turn into a big thing if I do. He can't handle my emotions right now, he just can't. So I need to. If I can do it sometimes, I can do it more frequently. So just for today, I will detach. I can do it one day at a time.
Is my thinking on the right track? Maybe the more I do it the easier it will be.
And what do I say if I don't agree with him? For example, if he says "my mother is right, you are xyz". Do I validate by saying "It must be hard for you to be in the middle of a disagreement between your mother and your wife? It is stressful to feel like you are being asked to choose sides?" What could I say to validate him without saying "your mom is right, I am a terrible wife" and without criticizing his mother?