RB, I have been worried about you. I am so sorry. I know that sort of pain, it is horrible. You have done all you can to encourage him. I am proud of you for keeping your own boundaries. Stay strong, hopefully he will choose rehab and learn other techniques to get through his pain.
My X is an artist (on the side) and he suffers from depression. It's always been a trigger for him, and I imagine always will be because he refuses to see his life in any other way. You are doing what you can, which is to put your focus on your own healing and choices.
We are always here for you. PM me anytime you need a buddy my dear friend. I am sorry you are hurting. You are both in my prayers.
Tight, tight, hugs.