I'm going to say I think I understand how you are feeling... why you are feeling as you are...
My mentor once told me (paraphrased), "If you don't agree with the game, stop playing."
It sounds like your H helped create the sitch you find yourself in, regarding talking about the D. ie. He used your past behaviour of not talking (which stung for you, because it was true) as a way to get you to do talk now about things you do not want to talk about.
He used PAST "more of the same" to create PRESENT "more of the same". And you felt guilty, so you're participating.
It is unfair to you, though. He manipulated you, to an extent...
that's the BAD news...
the "good" news is... he's found a way to get his needs met... ie. Since you wouldn't communicate with him in the past, something that obviously was what he needed (perhaps he's a quality time kind of guy), then he is using "bad" quality time... something is better than nothing perhaps, for him...
So stop the cycle... stop playing...
When he starts being all nicey, nicey... find a way to trigger yourself to spend some time with him in that frame... maybe 5 minutes... 10... you gauge based on what he has been doing... the amount of time it generally takes him to get to the "bad" stuff...
And before that ends, have some THING that you have to go to... to attend to... leave the conversation while it's on a good note, not on a bad note...
Change the pattern by changing YOUR pattern...
Eventually, he may stop trying to butter you up in order to have the bad convo. And he'll go straight to the bad convo, at which time you can simply mention that is for the Ls to take care of.
Both you and he are conditioning yourselves to have only GOOD quality time. The "tough talks" are no longer on the table, because your H wants a D. There's no need to "work things out" between the two of you. Focus on GOOD talks and GOOD time.
I can tell you without a shadow of a doubt... that's worked for me...
Also, I do not understand why you are taking on the job of working towards something HE wants and something that until at least recently, you did not...
You focusing on getting everything ready for the D... why are you doing that? Do you think that by doing all of this and getting things done quickly and efficiently, that this will end the problems?
And I don't think so. I think... and correct me if I'm wrong... that you are now quite angry... and I think it might be more accurate to say "livid" with your H. So you are just doing this and no longer just helping the D move along, but making things happen as quick as you can... because you are done... because of the anger...
So right now, that's "more of the same"...
So perhaps on that one, you can stop DOING towards the D until and unless you are requested to by your L and the proceedings.
Just because you are ready to D... just because your are done... doesn't mean that you have to start doing the D...