This is so hard.
I have never seen OW in entirety and do not plan to. But I feel inside this ghost who competes with me and seeks to destroy and steal every thing I have.
All I have left in the world is my two kids on my turn, my piano and my clothes, because they are too small for that woman.
I know the feeling you must have had before you did what you did. I know it well.
I don't know if it will help, but I think of the two of them here as feelings of huge entitlement. I was and am the villian that they created and they want to pretend there is a world without me in it, though I did nothing to "earn" all of this.
You see, I was/am the one standing in their way and I am also the one on the other side of parenting they have to contend with for the next 18+ years. I wonder because of the vehemence and competition he shows, if your X and POS may think something similar. It's mind boggling to think there is someone out in the world with so much hate for me and I didn't know she even existed for a long time.
And X (I hate to say "yours") in your situation may be fueled with adrenaline when Pos displays such behavior and it may egg him on, like a pattern?
I would bet, too, when you started to drive away that some adrenaline kicked in and got the better of you. It happens. But it's done. I hope there's a way to document it and put it out of your head.
Also, another thing I've seen and heard of is that when an x has really good response to this sh, the other side acts really rotten to provoke. Sometimes a good person is hard to make look bad, you know?