QS the idea is that if you hit her on her way out the door you RUIN her excitement and don't give her any time to plan a new approach or react... you hit her HARD with that moving out thing when she LEAST wants to hear it.
QS, the other thing you may want to consider here, and puppy can correct me if I am wrong, but you may want to consider exposing her plans to her parents... There is a RISK factor here, your wife's health, her safety, this guy clearly isn't on the up and up and I can't imagine parents would be thrilled at the idea of her planning to meet up with some creep that may just give her a disease or worse...
Parents DO want to protect their children from creeps usually... And anyone willing to sneak around like that and plan a meeting with a married woman specifically for sex is a major sleaze
