Can I keep my son in a stable surrondings

I am a Remarried father of one son, My remarried ex-wife and I share joint custody of our son, she was given domicile custody, but soon after the divorce, she requested that he lives with me out of state. I regestered him in Kindergarden, he is now in the sixth grade and has been with me every since.
Evethough my son is old enough to make his preference known about who he would like to live with, I'm afraid that she will take him out of state aginst his will during the Christmas holidays. Do I have a legal leg to stand on.

[tbyte]

OK, first, if the child has been in your primary care for the past several years, then you need to take some school records, doctors records, etc, to court and file a motion to be made the primary residential parent and seek child support.
Quickly. File a motion asking for an ex-parte order granting you temporary custody until the hearing, to prevent her from relocating your son and enrolling him in her local school system after the holiday break.
But, most likely the current orders grant both of you time with your son over Christmas, and there is no way you can prevent her from taking him home during her visitation. Your goal is simply to ensure that she brings him back.