Even I went through phases of this. A lot of vets around here suggest "I'm sorry you feel that way," for that kind of vitriol being thrown in your direction. Some suggest truth darts here and there. I think you asking him for ownership of 50%of the failure of the MR is a hill you can be willing to die on. Pick a line in the sand here. You don't need to validate every single thing ever to be DBing.
I just want you to know what he's saying is what he is feeling. Doesn't make it true. And while you can see that, he can't. He genuinely doesn't have the ability to see past his defense mechanisms and may I suggest if you can't give H some understanding here you approach his hot mess self with pity. It's patronizing. Probably just as much as saying "I'm sorry you feel that way," but at least it puts you in the right head space.
You will be ok no matter what. And if you want to stand, stand. If you don't, you go right ahead and throw in the towel. And if you want to fence sit for a bit to see how this separation plays out you're welcome to that too.
