Hi, all, OP here. Thought you might like a resolution. I appreciate the reality check here. I really was feeling a little gaslighted yesterday.
One thing that was kind of a non-issue is that yesterday was my birthday. After several hours of being badgered in between conference calls, I finally told DH what you all suggested: that he wasn't being fair, that if he wanted me to not go on this trip he had two years to say so, and that, frankly, he had made it a completely miserable day, thank you very much.
And yes, he did apologize profusely. He also told me that he had already contacted his boss and let him know that he wouldn't be able to go to the conference. I fumed for a little while, but the three of us did go out for a nice birthday dinner and it ended up being very pleasant.
This is pretty typical DH behavior. He really does want me to be happy, but he loses focus and starts acting like a child from time to time. I fret about it, but I also forget that it's pretty easy to shut it down; the hard part is knowing when it's happening.