let me get this straight? She is active with OM, but she is saying it is YOU who does not want to make it work?!
So, she is only willing to drop OM if she can ensure you back?
What you need is boundaries. "I do not want to be back with you as long as you are involved with OM" Simple. "we can entertain family parties together if there is no OM and you re willing to work on the M"
But right now, as she is in an active A, she has cojones to say what she did to you. IMHO.