Lewin, I want to join Ozzie in extending a warm welcome! You're in good company. You'll find support and encouragement here.

I'm so sorry you're dealing with this. I haven't been married as long as you have, but I know what it's like to feel hurt by your husband. Last year after I explained to my MIL that we'd agreed she wouldn't be moving in, my H turned into someone I didn't recognize, starting with a verbal assault for the two hour car ride home that didn't stop for several months. I had seen that side of him before, just never that bad. What you said about intense negative feelings that hang on for days...I understand. We started marriage counseling, I learned about BPD, and that's how I'm here.
My kids will not see him. They feel he gave a blanket apology and is not being held accountable. He has hurt them over the years. But overall had been a loving dad. He has always been easily angered and has intense negative feelings that hang on for days. He says his children have rejected him, though I have told him they are incredibly hurt that he hurt me, their mom.
My kids really struggle with their bio dad and their stepdad (my husband). I tell myself that my experience isn't theirs. I don't loop them in to my story or ask them to carry my burdens by oversharing. I let them have their feelings. All well and good, but when they avoid visiting because they're avoiding their stepdad, that gets really hard.
When I was 22 I learned that my NPD missionary dad had had affairs for 26 out of the 28 years they'd been married. Mom knew about it, but kept forgiving him and covering for him. When it finally hit the fan, you bet I was upset with him for hurting her. There are five of us kids, and each one reacted differently. It was incredibly helpful that she never stopped us from contacting him, she never resented us for trying to maintain a relationship with him, nor did she pressure us to do so. She was careful, especially at first, to not overshare information.
Sharing in the hopes that you know you're not alone and share little bits that helped me when I was in your kids' shoes.

I think your therapist has given you solid advice, and I believe you are strong enough to tackle whatever choice you make.
I'm glad you're here.
pj