Is it a criminal offense to falsify IRS documents

During my divorce my ex-husband and I were each 50% owners of a corporation. I did not work at the business. When he filed the corporate tax returns he claimed that I was paid as a 1099 employee. I did not receive a paycheck or profit sharing from the company. He did however pay my child support through the business then claimed that I received it as a 1099 employee. I was told by the IRS, that they do not have to follow court rulings and if he had my SS # and bank # then the burden of proof is on me. When I said it was child support they said it couldnt be if I received it from the business. I brought this to the attention of our divorce Judge. They said he could pay through the business as long as he claimed it on his personal taxes. He never did, now the IRS is saying I owe close to $500,000. Can I sue my ex-husband for this and if so would it be state or federal. I dont know where else to turn. Thank you so much.