go over to the dad forum... there's probably someone on there now going
"omg, my wife has just told me I have to take our 3 yr old on a playdate on saturday. should I stay or go? will the Mum be really scary??"
lol
i t'll be fine. if he is staying make him a cup of tea and have a chat.
and if he isn't, well that's fine too... just let them play and drink the tea by yourself! lol