Trusting my bf?

My bf been out of the country for 5 weeks for work. He came back and I guess added some chick from the other country on his social media. According to me they didn’t go out until the last night before they came home. I asked him and he said that apparently they added all his co workers and that I’m overreacting. I said you don’t just add random ass girls to your shit when you don’t even know them. And he got all mad and won’t talk to me. Am I being dramatic or insecure?