Well, you bought into it. You have to move on the issue. An out of state move is frowned upon more and more. And with not notice you sttod a good chance. The wiondow has closed.
Now that she "is established" since you did not file a motion (remember, she can move, you are requesting the kids to remain) there is not much you can do as far as enforcement. It is past 6 months so jurisdiction would mostly likey be with mom where she is now.
It is amazing how people will get 1 attorney opinion and run with it...I got 3 and glad I did