If you are in the USA consider filing a child support order with the state. You also have to consider that when you file this paperwork it will charge him back child support, with interest, plus current payments. If his income is severely limiited he may have a good chunk of his money taken out of his check each month before he gets it. He might not be able to make it on that amount. Maybe you can tell him you want to meet at a lawyer and make an arrangement instead of going through the state. The only problem I see is that the amount of money he pays you,it may not be as high as you think, since he is disabeled. I am not sure if the rate of child support is the same for disabled people because he has limited options to increase his income/

You cannot get support from his VA benefits. Yes, you will need to go to court and get child support payments up and running. If her doesn't pay, he goes to jail. Plain and simple.