HAL, First of all it's nice to hear from you, just wish you had some better news.
If he says he is ready to walk the line, I think you are going to have to confront him with everything you know and set some boundaries. He has definitely has a problem. Any chance he would go to individual counseling or marriage counseling?
Hugs
Life's challenges are not supposed to paralyze you, they're supposed to help you discover who you are. -- Bernice Johnson Reagon