T, I want to point out that they are the exact opposite of what they use to be...so...if he didn't like the beach before, he may very well enjoy it and he may not get bored w/the action on the beach, etc. He may like being by himself around you, but who is to say that he'll like it when he's away for a few days? I hop that I am wrong and if I am, I'm sorry if I rained on your parade today.
As for the Twinkle Twat, if she is going, she will pretzel herself into doing whatever it takes to make him happy...don't be surprised if he returns w/some new beach clothing and a nice tan. Oh yeah, she doesn't want to come in between you and your h, but she accomplished what she wanted w/that comment by planting weeds in your flower bed, so to speak. She's left you w/that comment to mull over all of the time and that is exactly up her alley. Please try to put that comment out of your mind; don't give her the power over your thought processes.
Oh, he'll choke on his sandwich, but not until he returns home. You have every right to be pissed.
Plan your fun time w/the boys and don't think twice about it.
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.