I'm sorry for the pain you're feeling, however you state that you were friends for 15 years before you decided to have a relationship. You should find it in your heart to forgive this guy and move on. Don't forget that his cowardice put a big dent in your friendship, and move on knowing that in forgiving him, you have taken the morally superior path and can stick it in his ear anytime you feel comfortable doing so.
It's his loss....don't let a wonderful vacation be tainted by something that happened afterward. Perhaps some day, you can double date with him and his girlfriend, and you and your new, rich, handsome, and much better equipped boyfriend (and believe me, there will be one).
My momma always told me "What goes 'round, comes 'round." If you wait long enough, he is bound to repeat his mistakes and you can stand back and laugh at him, or else sit back and enjoy the inner peace that letting go gives one.