I think you are lucky in some ways cause your W relationship with OW is over the top in some ways that I think it may blow over after this vacation.
Your W version of this OW is totally a fantasy and it seems unlikely that the OW is completely available to be in a relationship with a W from another country that has 3 kids. (Unless the OW is some kind of scam artist... you never know...)
I think you are right just keeping your cool about the vacation - don't let her see you sweat it.
Focus on yourself and your kids. 3 is definitely enough to keep you busy.
Do you have any hobbies?
---- M 39 H 35 D5,D4 M 4 T 9 ILYBNILWY 5/18/11 Left 7/11/11 Divorced 12/1/13