Yes, I'm sure I've said before, the most helpful thing a friend/neighbor/trained social worker said to me (in the more extreme case of an abusive former spouse) was, "OK, you have to decide how long you'll give this person to change.
"Don't tell them, but set a time limit, keep clarifying the situation, and if at the end of that time, the changes you need to see haven't happened, you have a new set of choices to make."
In that case, for safety and sanity's sake, it was a divorce, with former spouse still under a permanent restraining order.
That more surgical option was after three efforts to start couselling, each of which he broke off.
So, that's also a decision point, where there's physical as well as actual mental danger.
In cases where it's a constant acid drip of nonsense, you still do need time, space, and emotional distance for sanity's sake, and some of the other options, as outlined abovethread, are essential.
And it's important not to play "footsie," if you do decide that a full cut-off is necessary.
Former spouse and I attended the same high school. I do not attend alumni events or send little humblebraggy update notes to the Alumni news. In the past 40 years, there have been two really odd random run-ins at unexpected locations; I got out of sight and away as fast as possible.
As a result, I live a (mostly) calm, pleasant life, and I don't worry about stealth attacks and the like. (Thankfully, no children, so no need to stay connected for their sake, either.)
Maybe one has to go through one serious situation like that to clarify one's own standards or values, or sense of one's own value. I may forgive someone, but I don't have to trust them if they've shown themselves unrepentant and untrustworthy.
That's how spoiled children act.
M.