WH, keep track of all expenses related to the kids. My xh has also refused to share expenses, including medical and school costs, claiming he can't afford it, etc. This all started when his agenda changed. He bought a new house, car, appliances and likely other things that I'm not aware of. It's not going to look good when I present all of that along with proof that he paid over $1500 on his own teeth, but is refusing to split the boys' dentist bill which is minimal.
Your h's primary goal is keeping the house. I certainly hope the judge shoots down his desperate motion to reduce support. Have you made a current list of the new expenses you will have so that you can present them? I can't believe that your h fought so hard to get you out of the house and now he can't afford it. I can't imagine the judge will be happy with that. Since your name is on the loan I would request proof of payment each month until he refinances.
I am so glad that you are moving within days. Keep your h out of your new home. He will likely try to keep tabs on you and your spending. You might also set up communication parameters, limiting your contact to once a week, kids and finances only or whatever works for you. I think your h is going to continue to lash out at you. He doesn't show any respect to you and will likely think that he can disturb your peace by calling whenever he wants. I hope I'm wrong.
