First of all, thanks for the info. So, they stay with him one night a week and Mom is supporting them financially, as well.
I still don't see how you
working less hours enables him
to see his kids more often since they live with Mom. Can he see them on weekends? If he wants more time with his kids, he needs to speak with Mom. Maybe they can stay over more nights? Or every other weekend? This is not your problem.
He needs to stop being a jealous baby and live with what is. Or figure out what his issue is and address that appropriately (with the right person).
Do the kids even want more time with him?? Lotsa questions!