Oh DjV, I am so sorry that you had to go through that.
Think of it objectively - as hard as it is to separate yourself - you are a therapist. You know what depression sounds and looks like. He is seeing everything from a point of hopelessness at the moment. Like a black cloud he can’t shake. At least he can see the. Cloud, even if he can’t yet see his way through it. He has discovered his escape is not really an escape. He brings that cloud with him. My H is still trying to search for his happiness in other things and until he realises that it is in him he is never going to want to come home. Hang in there. It is not yet without hope. Keep doing what you’ve been doing.
Also - the fact that you did not feel as bad as you feared you would means that in some ways, if it does not end in R, you know deep down you will be ok.