Hi Sidony,
I'm pretty much the same as yourself. It's difficult enough for me just to talk to someone privately, never mind in a group and particularly when there's a feeling or pressure on me to say something. Are you being pushed into doing the group? I don't think it helps if you're forced into it especially if you come away feeling worse. I do feel a pressure while in a group and panic inwardly. I can just about deal with maybe 3 other people but then depends on their personalities. If someone is overbearing then I can't say a thing. At times it's not that I don't want to talk, I can't talk. The words get stuck in my throat. I don't know if most of it comes from self-worth. If you feel that what you have to say is worthless then it's not likely you will say it or look like a fool for saying it. But then most of the time while listening to someone else in a group talking I think they are talking crap so maybe you should just join along and see how much crap you can create between you.

Next time you are along, make it a competition to see who can talk the most crap. Don't take it seriously. And take a shovel with you, just in case!