I'm in a similar stitch but I know the more i've pulled back the more my W has stepped forward. With that being said, last night W again said she can't do this to S. i listened, validated but told her as long as she continues contact with OM their can not be a R but we are moving forward. W is in control of the direction based our her decisions which I can not control. If she wants to be with me their can not be any contact with OM. But continued contact is a deal breaker for me. That is not control, that is me doing what is best for son and me. As I said to my W you can do what you want and I want you to be happy, however I'm not willing to be in an open M. The choice is theirs, we are not controlling. We are only responding or acting based on their continued behavior. Don't believe a word of it.
And THAT, folks, is the difference between "controlling/ultimatums" and "strong loving boundaries." It's the difference between making it about THEM, and making it about YOU. It's "you can do whatever you want, but only outside of my circle. If you want to be in MY circle, this is what I allow inside of it. You decide."