I had something similar happen to me. Every year we do one or two tropical vacations at nice hotels. This time, it happened that the trip was four days after BD. I persuaded my WW to continue with the trip for the sake of S11, but we were miserable. She wouldn't show any affection toward me, was as cold as a fish, and never smiled the whole time there. I was the cheerleader trying to everyone to have fun. S11 did enjoy the trip but I'm sure he felt the tension as well. My hope that she will relax and think about reconciling was absolutely impossible.
I also considered when I discovered her EA to keep quiet about it until after the trip. But I think I would have literally gone crazy.
Point is, be prepared emotionally for what will happen on the vacation.
Me-LBH, 48 Spouse-WW, 48 Married for 19 years Son, 12 BD #1 - November 1998 (EA 7 months after wedding) BD #2 - November 2015 (same XBF EA) WW filed D February 2016 WW moved out April 2016