He said he would do anything to stay in your life but your answer was still about him. Your focus is all about him. He was asking you what you needed.
Of course we want them to get well, be strong and thrive. That is never a question. But don't you need him to be there for you as much? He may have been in the past but what about his capacity now? It is next to none I'd wager because recovery is a selfish thing. It is about learning to love themselves first.
(I am writing this just a much for myself an in response to your post btw).
And of course he is scared sh*tless if you pull back. He has a person who loves him unconditionally and it requires next to zero effort on his part. I think your therapist senses that you are going to deplete yourelf if your focus is just on him. You will neglect your own life and the ability to be successful in it because of the energy and time you give to him.
I'm going to toss this out there: is there something going on in your life which you should be focusing on but are making him the 'distraction'? I do it all the time.
Finally, that distance thing. I'm in a similar situation and because I have no clue what he is up to really, my thinking about and assessing him is a form of control I exert on a situation I really have NO control over.
You can still be there for him. Still love and care and wish him the best. But honestly your approach isn't helping him. You have to let him fail and grow in the process. Nothing you do will prevent that. Nothing.
Lastly, as someone pointed out, 5 months isn't long at all. Buckle up because it will be a bumpy ride.