Well... I'm probably not the best person to be replying to this post since I left my parents behind many years ago. (They're both deceased now.) It was a complicated situation. And it was all, perhaps, as much or more my fault as it was theirs. I'll spare you the details)

What I would say though, with regard to your post, is first of all avoid as much as possible continuing to be caught up in what occurred between your father & your mother. That was their story... not yours. Of course it affected you. But that too is in the past now. So try to leave what is in the past... in the past... if you can. (If you cannot, perhaps that's where seeking the services of a mental health therapist comes in.)

Try, if you can, to imagine yourself when you're oh... say... 50 years old yourself. How will you feel looking back about how you handled your relationships with your parents? If you honestly feel you can cut one or both of them out of your life & feel comfortable with the fact that you did it, then fine. But if you imagine it's likely you'll regret having done so, then I would encourage you to at least try to keep the lines of communication open. This will most definitely require you to establish & enforce some personal boundaries. You're an adult now too. And you have the right, I might say even the duty (to yourself), to say what you will & won't accept from each of your parents. If they can't live with the boundaries you establish, they also can choose to walk away. My best wishes to you...