"As it stands for you in 2019, you have every legal right to claim your son as your dependent."
No, you do not have EVERY legal right. You just have the right under the IRS rules. This assumes the divorce degree is dated after 2008. So, the IRS will let you claim him. But if the divorce decree is still valid (it's not clear that it is), your ex can take you back to family court. The judge has no authority over the IRS. But he does have authority over you. He can order you to pay her, fine you and/or throw you in jail for contempt of court, for not complying with the order.
