As hard as it may be and as painful as it may feel...
An answer given in a mono tone voice that says...If that is your choice (and say nothing more)
What that will do is have him thinking on things and let him know that it is his choice. As his ego and self esteem go up and down, he may continue in the flip flop of choices.
Continue to work on your own needs. Rather then sessions...Al Anon meetings or Nar Anon meetings may gain you needed answers.