Why not just discuss it on the telephone? This sounds like a ploy to get you in a public place so she can start talking about things you don't want to talk about.
If you go, remember the boundary? If she wants to discuss divorce/properties, remind her that she agreed to talk about your son and that's it.
Me: 47, Ds 17-13, D final 6-11 http://tinyurl.com/yk4e2tz http://tiny.cc/thread2 http://tinyurl.com/ydtphqu http://tinyurl.com/thread4 http://tinyurl.com/3sm78k6 http://tinyurl.com/thread6