In the end, I decided not to go with her. I emailed that I had other plans, and brought her up to date up on the kid/school stuff. Ignored the "business" she mentioned talking about. If it's so important, well she knows where I live.
The thing that made me decide what to do was this:
I asked myself what was best for me.
I decided that I just did not want to sit with her in a pub to hear all about her MLC vacation. To feign interest in people that are 30 years removed from her life. That I did not want to be her dependable friend whom she just happens to be suing for divorce. That I did not feel like being her support group for whatever it is she needs right now. Especially since it seems that what she needs right now is some of my time and attention. As ForeverYoung said, "New guy makes the cake".
And it also occurred to me that I have never rejected her invitations, for anything, ever. It occurred to me that it might be nice once for her to feel my rejection, and to wonder what is happening, and what it means.
Me:52 Wife:49 Married 19 years Son:16 Daughter:14 Bomb dropped with ILYBNILWY: May 2013 Wife moved out 2Jun13