holiday boyfriend problems?

so my bf and i are on uni holidays for a few weeks and planned a 4 day trip with a group of friends, and we got really excited about it but were upset when it got cancelled, decided to just make our own fun for the few days... but just today he told me that he is going on a different trip with 7 other people.. for 6 days.. but i wasn't invited. I'm actually good friends with these people as well, even though they were originally all his friends. so I'm upset, but he was so excited about it that i just pretended i was excited for him.. :/ what should i do.. ?

and he is not the type of guy to cheat so I'm not worried about that. but i am frustrated because i know he is going to smoke weed cause one of his friends in particular does and.. has kinda persuaded everyone else to... and he knows that i HATE it!! he doesn't do it often.. but this week will be full of it.. i don't want to say anything because i don't want to be the "nagging gf" but at the same time i want to tell him it annoys me :(