Stop sending extra. Only send what is court ordered.

My ex and I had our kids start school at age 6, as it seemed to be the best for them. I have to pay an extra year of CS because of that decision back then. So be it. It was the right choice for the kids.

As for your husband, he had equal say in whether the child should be held back in Kindergarten, but apparently he didn't. That was his responsibility if he felt differently.

Beyond that, CS is almost over for you.