Many of us have someone like that. When I lived in Spokane and was in my first marriage, I had a friend Roy. We had such fun together, fixing cars, getting high, and laughing ourselves sick. My wife ran away with him, taking our son who was I think 2.
About a year later she contacted me saying Roy was in jail because she had him arrested when he took her checkbook to the bar (into which he had "moved") and tried to cash a check he had forged & could I help her GTF out of there? In those days $500 for airfare was a lot of money for me but I didn't hesitate.
Only much later did I learn the extent of his brutality toward my ex and my then 3 year old son.
We don't know what became of him but hope he is dead and that he died a miserable, lonely, drawn-out, excruciating and humiliating death. I know I shouldn't wish such a thing on anyone but in honesty that's where I am.