A friend had this exact problem fifteen years ago. In the end, she asked him to leave, expaining the problem it was causing with the children. He left, and set up in a bedsit. He lost his business (pressure there had been part of the cause), his self- respect, only the core of the wonderful man we had known remained, and we were expecting any day the news that he'd either crashed his car or gassed himself with the exhaust. Then, one day, he was arrested for drunk driving (a miracle it hadn't happened before), and banned from driving for several years. That humiliation released some locked-in strength. Without telling anyone, he arranged to go to AA meetings, went into a hostel, dried out and STAYED dried out.

Not entirely a happy ending- they didn't get back together, but she's still friendly with him and they have both rebuilt their lives. But it was her strong action that precipitated the whole chain of events. Be tough. He needs it.