Wow! That is a LOT to deal with. I can't imagine the emotions you must be experiencing. I can understand that the second time would leave you a lot less willing to overlook and forgive. You sure would have thought it would have scared him straight but it doesn't.
Our stepdaughter has been gone for over 5 months on her latest drug binge. No car, no job, no place to live and everyone else caring for the kids she left behind, she is 35. You would think rock bottom would get old but she is still going strong. She had also taken 3 trips in an ambulance for overdosing over the years in front of her kids. There is no easy answer.
Not saying not to give the guy a chance but don't let him take you down with him! Good Luck!