My Gf sometimes brings her friends to hangout together/get to know them, but I usually don't take the lead when it comes to group situations like this. I just follow and tell when I don't agree with something. I'm also very quiet, I don't talk much it is like I'm in the fight and flight mode, that someone can throw a shit test on me anytime, so I dont function properly and that only in Groups. I also can't hold a conversation because I feel like it is exhausting to adapt to someone unknown in groups, especially if it is a friend of your GF and in your mind you want to make a good impression. Any advice, that helps me to work through this?

Thanks in advance