There is no right or wrong way to deal w/someone who is in crisis. What you have done in the way of messages as a friend, is working for you.
If we all go back and think of long ago, we started out as friends w/our spouses/companions and that's where the new relationship needs to start...as acquaintances and then on to being friends.
By being a friend, you've taken the pressure off of him to get him to return home and "shape up and be the man you were". You've allowed him the time and space to think and stay in touch w/his children. He can now do this w/o thinking that you are judging him in all areas. He feels "safe".
I think you've been doing a good job of keeping it together and also keeping your expectations at a low level. Continue to do what works in your situation and when something doesn't work, toss it aside and try something else. After all, there is no rule book on how to deal w/crisis people and each person needs to right their own manual for their own situation.
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.