Still I think that your offer to move closer is in your best interests and the child's. The mother and her lawyer will cringe when they hear of your plan to move closer. It is exactly what they were hoping to avoid. She had probably hoped to use moving further away as a way to weasel out of the 50/50 parenting plan in the first place.
She has been playing games. Here's hoping tomorrow you put it all to an end for your child.