GG, finances seems like a thing to talk about in a safe place - like counseling maybe. I'm with you, the finances wouldn't be messy if he lived in the same house with you.
On the other hand I can see his point. "my money is my money" is a stance of independence. He is still struggling with how to balance the commitments he made to you and the family, versus his internal selfish desire to be completely independent.
Seems like there is a battle inside him going on - the selfish versus the giving. The bachelor versus the husband. And it seems like the husband is mostly winning, but the battle still rages.
PH - about getting the motivation to bake or cook - the key thing for me is to have someone to share it with. even if I cook or bake alone (yes, I bake) i need to have someone to share it with. you know last christmas my sister sent me a batch of cookies, across the country. it was so nice to receive. maybe there is someone you can think of who would smile if they received some of your christmas baking. a neighbor? a friend? someone older in a residence home nearby? a school? even a shop you frequent?
Do it for someone else, do it to share the good will of Christmas with another soul. it feels good!