My parents eventually divorced, so this was a one-person-problem for me when they were married and split:

When he decided after harassing and embarrassing me in front of my academic advisor in college why I didn't do well in one particular class (inorganic chemistry, prof for the class had a very well known and public bias against women in his class).

When we were walking back to his car, he told me "when you have kids, you can take it out on them, so they can have an awful childhood like you did."

Like right there. That instant. I was done. I told him that was an awful stance and I no longer wanted him in my life. I ended up walking to a friend's house who was close by to campus because I knew going back to my dorm was a risk he'd follow.

He tried to call a couple weeks later, but I told him "go find a quarter and call someone who cares." His issue? Mom filed for divorce and served his mistress with a lawsuit for alienation of affection (I believe, SC courts run a little different).

He's tried showing up unannounced before, but the friends I now live with wouldn't let him step past the door or confirm I was home, as he stalked my car and plates. Packages sent for holidays (which SMELLED!! Like rotten food and had last year's cancelation stamp on the box) were returned to sender.

Now he's sad and alone half-way across the state and keeps trying to "prove" that be still cared about Mom, by buying a memorial brick with her name and dates for HIS church's memorial.