i'm curious what you think assisting him with recovery looks like? you've BEEN there in the wings for a while now, ready to serve! and it has not affected his addiction one whit.
i think you are grasping at straws. wanting to remain involved. wanting to own a piece of it.
IF he decides to seek recovery, i hope he turns to recognized recovery programs, gets involved with other recovering addicts, and gets busy walking the path. there just isn't a lot for a "friend" to do in this case....
wish him well, and stay focused on the wonderful world of YOU!