I like Sotto's changes, but I would remove the sentence saying you are "sure" your son will have lunch with her. It goes against the idea of letting him choose. Maybe instead suggest she contact S directly about lunch?
Me: 44 H: 44 Kids: 20, 16, 16, and 10 Together/Married: 22 years H announced he was emotionally detached and considering D: 4/4/16 H announced he is going to try to stay and reconnect: 5/1/16