That made me cry.
I don't know what to say about your idea to drive there, because I don't feel like I have enough information.
Based on my experience of the American court system when it comes to custody, however, I'm willing to venture a guess that the children's mother is either mentally ill or violent or both -- because I know what my AXH did to our children, and his protective order gets reevaluated twice a year. To get a firm one till the kids are 18, the courts have had to be convinced that she is very much unfit to be around them.
Heartbreaking as it is, I would not do anything to jeopardize the existing court order, as it is giving your children a solid protection I assume they need.