As you know by now I am no expert in this DBing stuff, but I think it is time to consult with a L. I am no legal expert, but they will know the laws in your country. Again. your H is controlling all of the action.
My 1st marriage my W made more money than me, but she is the custodial parent so I pay child support, plus a third for medical, social clubs (Boy scout dues), etc . You are the custodial parent so he will have to pay child support plus additional expenses....get a lawyer!!!!!