The divorce agreement is between the parents, not the school. Parent 1 would have to bring Parent 2 to court to enforce.
Sometimes reasoning with the parent is the better way to go. “Parent 2, I know by the divorce decree that you are supposed to pay $$$. How much can you pay?”
It might be easier in the long run to just go to a FAFSA only school where you’ll get a good merit scholarship and maybe some FA. If you fight, you’ll probably be fighting all 4-5 years of college.