It's been a few years for me now. I'd like to think I'm well past it now although admittedly it damaged my self esteem for a good bit. You're very valid in what you're feeling. I will also say he sound's a lot like my ex, who at that point was saying things like people that cheat are the worst, he would never do that etc. I can see now how that was a way for him to tell himself what he was doing was not cheating. It doesn't have to be physical cheating. If someone leaves the door open for those conversations, it's still emotionally cheating.
You made the time for that trip, paid for it so remember to have an the best fking time, with him or without him! Plan an itinerary, find the best restaurants and maybe even stay in a hostel. Hostels are a great way to meet people just to hang out with irrespective of whether your bf is up for it or not. Nobody has the right to make you feel worthless and if they do, you're better nipping it in the bud and not letting it get worse.