Hi bananas2,
Glad to hear that you were able to communicate about it

And good job on the validation and stating your truth

Although the crisis might be over for now, I thought I'd chime in for others that might be reading the thread as my dBPDh has been in therapy for 2,5 years now.
He did see and art therapist/psychologist for a few months some years back (maybe four years ago?). One day he just stopped. I didn't really see much difference. Then he decided to start doing psychoanalysis. He has been going twice a week for 2,5 years now.
And yes, it has stirred up all kinds of emotions along the way for him. I have been extremely frustrated and struggling with it as well, and it has shown me clearly where my own issues lies, too. The last few months he has seemed a lot worse, and then suddenly things has started to fall more into place. He has opened up more and has shown more insight the last couple of months than our whole time (7 years) combined. So it might look messy, chaotic and volatile from the outside. It probably feels like that as well. I guess it's normal, because feelings are bubbling up to the surface and he might face some harsh truths about his himself and his relationship with other people.
My husband has very recently been able to express that when he is "experiencing a crisis" (dysregulating), it has nothing to do with me. I'm there as a trigger and a target, but he's really struggling with issues that go way back into his past. And that he's in tremendous pain during these moments. And although he doesn't want them to happen, he has no way of stopping the wave of rage and emotion when it arrives. So the best thing I can do for him and myself, according to him, is to remove myself from the situation. Because it's not me he can't stand for one more second, it's the situation itself, which at that moment triggers a ton of hurt and suffering for him and makes him go into protection mode, which is rage. This is all according to him, and seems to align with what we learn here. He says taht in the heat of the moment, he doesn't see it and he is uncapable of stopping it. He can talk about it after, though. So he really, really wants me to remove myself from the situation, for both our sakes and because he wants to do as little damage to our relationship as possible. And he knows that he has no way of stopping what is happening. I really need to get out of the way.
The fact that he's projecting situations and feelings onto me is not news to me, or to any of us here I think. But it's a great breakthrough for him. And this breakthrough, or change in understanding, came after a really messy, caotic and volatile few months. Beacuse therapy is not linear, it's not "Now we've fixed problem A, let's get on with problem B". And the patient is constantly faced with triggering, difficult, exhausting truths. No wonder the person has little control after, with lots of "demons" coming to the surface.
So in short (

), it seems normal that it triggers all kinds of crappy feelings for your husband. And make sure to distance yourself from it.
It's possible it feels somewhat the same for your husband.