Did you tell her not to contact you unless it was something extremely important about the kids? If you did, then I would let it go to voice mail.....at least until you get detached.
It sounds as if she may have tested you a bit just to see how you would respond. There are a lot of women who go to great lengths to test the LBH to see if she still has an affect on him.
Don't be shocked when she completely ignores what you've said. Like you said, she already has on the first day. I think she will even want to hit you up for another "family activity" when she gets bored or lonely. It is hard to explain why some women do this, but it's part of the cake they want.
You will figure out a way.
It is not about what you feel should work in your M. It is about doing the work that gets the right results. Do what works!
