Mama,
Forget the OW! You are on vacation and this is a time to create the most wonderful of times together. Let her have her stinking phone call, you got the real thing. If you let the OW destroy this chance to make a positive impact on your R then it is you, not H, who is sinking the ship right now. Hope that doesn't sound too harsh cuz I know what kind of s*** you're dealing with here. My W used to make the odd phonecall to the OP when we were away and I just let it sail over my head. Again, when they have to sneak around to talk to the OP they are degrading themselves more than us! Lastly, if she (OW) is really pissed with him for going, you can be a ray of sunshine and who's he gonna want to be with? Stay positive, stay focused and have some fun, fun, fun (with or without him).