You cannot control what happens out of your house. That is completely out of your hands in respect to the OM. However, you can have the no-OM boundary in YOUR own house.
Yeah, stick with 50-50 custody. As for moving, I'd stay where you are. It is W who MOVED AWAY...not you. It is her problem. Continue working with your L on this. I think this is your best shot.
I am so sorry that your W is being obstinate about this issue. Ugh.