<human>: Can you give me the gist of the text in a nutshell?

Ok, hello Reddit ! First time here but I really need someone to talk to.

So in short here's the plot :

My GF of 3 years (we are are both 20 yo) left last night (gmt+1) for a 4 days citytrip in Bratislava with 3 female friends. They are staying in a youth hostel and sleep in a mixed room (i.e. with potentially 16 other boys/girls). I texted her this morning to see if everything was alright and she said that yes, the city was fine and that she just had taken a nap. She also said french boys were sleeping next to them and that it was a bit awkward. I just texted her (it's 11:50 pm here and there), asking many questions and she simply replied "We've met a group of french and belgian boys and were are leaving to have a drink with them, it's cool! How are you?". Needless to say I didn't react well. However I didn't tell her, I don't want to ruin her trip. 

A little background info : it's the fourth time she goes on a trip with her female friends, everytime there's a lot of partying and they always end up meeting foreing boys (Never encoutered any girls, I must have bad luck). The very first time she left we had a bad time because I found hidden pictures of her on somebody's laps and very close dancing (and worse) in her computer ! She has always been a little naive (if not stupid), she thought boys in night clubs only wanted to dance and pay her drinks to be friends. I've told her numerous times but she's always being hit on every night out..

Do you think I'm being jealous? Should I tell her how I feel? What should I do?

Thanks !
<bot>: GF with female friends in another country. Met boys and goes out drinking with them. Me angry/jealous, don't know what to do