"He treated me with basic human respect for a few years!"
Yeah? So fucking what?
If he isn't doing that now, that means he's now trash, even if he feels like whatever; you either treat people decently, or you don't.
And if you don't get treated with basic human dignity, and they start treating you like shit over and over again, you stop helping those people.
Dumbass.
That's literally how narcissists snare their victims.