Even at school I often sit by myself in classes because I can't talk to people openly. That leaves introverts in the minority, which doesn't mean introverts are wrong. I'm an introvert. I generally process feelings by myself, rather than with a gang. People are different from each other.
Some people love bungie jumping, while others enjoy operating on elbows.
You did fine for a couple of days, but it sounds like a week was too long. Frankly, there is hardly any group I could spend a week with without partially deteriorating. There was a group of therapists I did serious work with working with survivors and offenders of sexual child abuse. Then every year we went to a conference center near the ocean to recover by laughing and being silly. I thoroughly enjoyed their company and went on vacation with them for years after I stopped working with their group.