Yes, YTA from start to finish.

It's a business trip, not bonding time. Inviting yourself isn't great to begin with, but going and then complaining the entire time is even worse. Traveling for work is generally pretty grueling - traveling for work internationally is even more so. You have to fight through the jet lag and often feel like you don't know if you're coming or going, but that's just how these things work.

What you should've done is asked him to tack on a few days at the end of the trip, whatever country he was going to be in then, and just met him there for a few days of rest and relaxation. That would've been easier for both of you, and would've given you actual quality time together.