What shoudl I do ? Is it too late for me to go to the courthouse to file the paperwork.?

Ok you gave her written permission to move out of state but not out of the country. She can get into some real trouble doing that and could lose custody if she does and you can tell her that. You can sue her for breach of contract if the agreement between you two spells out everything; support, visitation, etc. You can stop her from leaving the country with your child at least. As long as shes still in country its never too late. You can charge her with federalparental kidnapping if she leaves the country and there is no where in the world she can hide where the law wont find her and especially your child. Good luck