I'm so sorry this is happening. I know the feeling. Hubby invited me to join him on a work trip in Seattle, but it would be at a hotel. My pups do not like being left and I could never leave them in the hotel as they would bark the entire time. I have chosen not to go and get some things done at home instead.
Have you tried turning on the tv for some white noise and giving him treats so he realizes that when you leave he gets yummy things?
It's crummy not to be able to enjoy the beach together...