So sorry you are going through this. I wanted to let you know that I've read your post and feel for you, and I have a few ideas.

I understand that you don't want to feel that you've broken your promise to never give up on your son. I think you can view this another way though successfully.

By taking good care of yourself and making sure there are consequences for his actions, you are doing the best you can for him. Calling the police, having him escorted off the property, even filing a restraining order could all be positive actions for both you and your son.

You won't do him any good if you let him continue as is.

There is help available to both of you. Safety concerns come first. I understand the urge to disappear but you could also work to be more visible, get into therapy if you aren't already, tell people what is happening, get help.

I was abused as a child, I've had a rough life, but that would never ever be an excuse for me to abuse another person.

He doesn't have the right to abuse you.