You have a complicated dynamic going on. You are making 180s by showing you are there to support your H. At the same time, you are on guard about being overly appeasing and making the whole process easy for him (sometimes called "playing family").
I'm going to put a Zen twist on this. Maybe it has nothing to do with whether or not you invite him for Thanksgiving, and everything to do with your own mindset.
Can you be that soft place to land, while also letting go of all expectations for what it will mean? What if he joins you at Thanksgiving, and then continues pushing for D as if nothing happened? How will you handle that emotionally? What if he keeps leaning on you for emotional support month after month, and then pushes the D through anyways?
I don't know if this makes any sense. We all come here asking for advice how to handle situations X, Y, Z. The longer I've been doing DB, the more I think that the actual decisions we make each day don't matter all that much. Sometimes they do, often they do not. It's all about mindset. Because that will shine through, that will drive your decision-making, your tone of voice, the facial expressions you make during a difficult conversation, how you phrase a text message, everything.
All of this said, I have no idea what you should do, and I'm sorry I can't be more helpful. Give him a soft landing? Or let him experience what he will lose with a D? That's the thing. We have zero control over other people, zero control over how they will react. We are all in our own Twilight Zone situations that are so bizarre it is impossible to predict how people will behave. Accept it, embrace it.
Whatever you decide to do, I hope you can find your center and make a decision that you trust to your core.
