My experience of men is that they only think of themselves and are really surprised when they see that we are thriving without them. It has all been about him and what he wants. He expects you to be on the floor in a mess, and that boosts his ego. He doesn't understand why you aren't playing ball.
If you can, I would be winding him up big time.
Can you have the kids on Sat as I am getting a tattoo.
"No, sorry. I am going away for the weekend/ I've arranged to go out all day, then I am out for dinner that night too".
Don't be available. Delay texts back. Let him think that when he left you and the DC you were devastated at first, but now you have had 3 months to get used to it, you can see that yeah, it's for the best. You have moved on, you have filed for divorce from him. You thought it would be awful, but now you and the DC are THRIVING without him.
Tell him you can't as you are going the gym/cinema/out with a friend/ going on a day trip/ secret squirrel not mentioning where you are going.
Honestly, even if you don't feel it, if it is definitely over, whenever you see him or talk to him give him the impression that you are thriving without him and it is like you have been reborn. If he asks for info tell him it is non of his business, you aren't married any more.