What helped me is imagining my life in 1, 5, 10 years. Doing exact same thing. Worrying about him driving DS while under influence
I kicked my XAHs rear every step to his PhD
I was his ultimate cheerleader (he did not return the favor)
I was on never ending quest, looking for ways to cheer him up, scheduling date nights, making sure he feels like a man (he chose not to work full time)
What I got in return was stolen money, lies, more lies, rehabs (and lots of hard earned money (by me) flushed down the toilet when he decided to flee his last rehab, most likely with some sort of alchy GF (I did not look much into that matter - but rehab people stated that his wife checked him out lol).
I also happen to be 14 years his junior - I definitely feel that he was not changing and I need to move on.
I have had my weak moments. What helped me is making a list of "why I am letting him go". Revisiting it helped a lot.