So, finally you are tired of being taken advantage of. They have been counting on you being a doormat and have behaved toward you accordingly. That is done now. Be prepared of their righteous indignation and whining over this. If they start blaming you, tell them if they had not made such bad choices you wouldn't have had any reason to make any calls. They made their own bed.
Now, drop his crip off in this mother's front yard. Really, put it in garbage bags and just dump it...on a rainy day preferably. Be done with him a move on with your life.
my grandmother use to have a saying - 'crazy people only respond to crazy' as you said you tried and enough is enough.
hopefully, now, finally they will get it - you are not a pushover and certainly NO dummy.
he wanted her, now he can have her - lock, stock, and barrel.
now is your time, to live, laugh, smile, enjoy, but most of all be at peace that it is finally o v e r. start making plans, do not just think them in your mind, say them outloud, and write them down.