I need some honest advice

[Drew]

So you need to decide what you will do when she disrespects your boundary.

Again, boundaries aren't to control another person. She's right - she can do what she wants when she wants. As can you.
Boundaries are how you will tolerate other people treating you.

A better way to put it is: If you _____, I will _____.

For example, if you continue to text OM in front of the children, I will be forced to ........

-Take the children and leave the room
-Take the children and leave the house
-Stop paying for your cell phone

That's what's under your control.