Well, I would play it out in your mind a few times just so your prepared and calm and cool. I would not show any emotion are discuss your state. Just keep it friendly and short...life is good, no worries. Make her wonder. Be mysterious. Your're on your way to a party or something fun and out of character. No details.
Hope this helps!
Formerly SGfan M:38 W:33 M:8 yrs T:10 yrs Bomb: Dec '08 Separated: 4/18/09 Divorce: 8/28/09 XW Affair began: April 08