Rather than explicitly praising his good behavior, maybe there are other, more subtle ways to reinforce, like smiling at him, engaging with him, etc. Have you read the 7 Principles? Not saying this was good or bad from a DB (or eventual outcome) perspective, but the two things I changed in my own behavior last spring after DB1 when my H was a total and complete a**hole all day long and resentment basically rolled off him in waves every time we were in the same room was to start paying attention to his bids and validating. If he would talk to me nicely or ask me something, I would put down what I was doing and listen and validate rather than do it with half my attention and point out the flaws. If he complained about something stupid like how I loaded the DW, instead of getting angry back and fueling the fire I just validated-- I see how that would be frustrating. Those simple changes with a little bit of time really changed our interactions and the funny, fun, not-angry-all-the-time H came back.
Course, he's still not in love with me and all that and my H hasn't gone quite as far off the deep end in terms of his behaviors at home as yours-- but as long as you are subtle about it, can keep a happy attitude and just be nice and responsive (and validating) when you do see the old H peeking out, it might help without seeming like you're being his mom and still giving him the space he desires.
You're strong. Don't let him drag you down.
Me (46) H (42) M:14 T:18, D9 & D11 4/19 - 12/19: series of escalating BDs 9/20 - present: R and piecing
and my H hasn't gone quite as far off the deep end in terms of his behaviors at home as yours-- but as long as you are subtle about it, can keep a happy attitude and just be nice and responsive (and validating) when you do see the old H peeking out, it might help without seeming like you're being his mom and still giving him the space he desires.