one thing I read somewhere, which was really powerful to me, was that pretty much all human communication can be boiled down to 'please can I have this' or 'thank you for this' or 'yes I will give you this' or 'no I can't give you that.'
It has helped me listen to H differently. Now I listen for the request, and decide if my answer is 'yes I will give you this' or 'no I can't give you that'. Sometimes he is venting and by doing that he seems to be asking 'please will you listen to me as I find that comforting' or 'please will you do or say something so that I feel different'. As soon as I have identified the request - or understand that he is giving a 'yes' or a 'no' to one of mine, I act accordingly.
It can take a while to understand what the request is. Sometimes someone seems to want reassurance, but they actually want you to take the blame. Sometimes someone wants permission to set a boundary, or reassurance that if they do set a boundary, the other won't be angry or withdraw. I think adult communication involves staying in the moment, making requests and not demands, and being clear in your yes and no. It's simple, and also very difficult.
I think your husband is repeatedly saying some version of 'please will you make me feel better' - his fantasy D was about feeling better. Working on you to accept blame was about making him feel better. Agreeing to the trip then agreeing to being friends after the D wasn't about those things really but about making him feel better. Now, him wanting help through his process, and reassurance about what the future will look like, and signs of your commitment are all about him wanting you to make him feel better. I don't think you need to say many words to answer those requests. You can just gently step away and live your no. He NEEDS to feel some pain or he won't change. You aren't punishing him, you're just saying no to what he is asking for.