It sounds like hubby has some other issue going on. I don't know what, but he will have to make up his mind to tell you what's bugging him or not. And I would devoutly hope that he knows that sulking at you and crying in his pillow is not really a successful marriage tactic, but maybe he needs a gentle reminder that you love him very much and are trying to be understanding. You're his friend, not his mom, and he's not a child.
From what you've posted, I do not honestly think that he is seriously angry about a 5 year old discussion that was so trivial you don't recall it, or really and truly upset that you would want to go to your brother's wedding in your parents' company. I mean, it's not like you are running off to meet Brad Pitt and Robert Downey Jr. for cocktails in Key West. You are not running away to join the roller derby, right? You're not signing up for a mysterious cult that worships sunny beaches and lime trees, are you? You're not even doing anything that he might fret slightly about, such as traveling alone or spending a bunch of his money, since Mom and Dad are paying. Grown adults, even married ones, occasionally spend time apart for more than 20 minutes without getting divorced. Honestly. Only he knows for sure, but I would bet there is some other motive going on. Because this is not the want or demand of someone who doesn't have a grudge or an ulterior motive.