It's possible he has some mental health problems and tried to self-medicate, with the predictable results.
I appreciate your desire to diagnose--because within that there's hope of a remedy--but really, you can't be a professional here. Your home and your life can't be a mental health ward. Someone else has to help him now.
There are two possible diagnoses, with attendant outcomes:
1. He's got problems that cause him to be intolerable to live with. He has enough clarity to see these and wish things to be different, and can reach out to all the help that's out there so he can move from point A to point B. In that case, sure, there might be hope for the marriage, but only if he works hard to sort himself out--on his own. Time will tell.
2. He's got problems that cause him to be intolerable to live with. He lacks sufficient clarity to see this, and blames others. He doesn't change, most likely gets worse.
In both these options, a period of separation is key. It's GREAT that he's moved out. Living with The Crazy for so long, you could benefit from the time to get your head straight and just enjoy the healing peace and quiet. Give yourself a year, tell yourself you're just going to heal and be peaceful for a year without him, and then see where you're at.