No easy answer to this. I assume he is seeing a therapist, and have gone to rehab. Have they tried CBT? Does he have a concrete plan in mind as to how he further advances to his goals? Does he even want to?

The right answer may be to fully support him during these difficult times, which will help you both rise to brighter times. Alternatively, the right answer might be to properly leave him for a period of time, and hopefully make him go somewhere else - change of place, change of luck, this might be the thing that will ultimately allow him to break the cycle. I don't think that any internet stranger can tell you what's the right thing to do, you probably have to sit it out with him and decide for yourselves. Also, yes, as comment above said, drop the straight nonsense completely.