I absolutely hate this group I'm in.
Why? What did they do to you?
Almost every person in this group is a complete jerk, I can't believe they don't know how much of an asshole they are. That's why I want to leave the group.
If possible, leave the group. Life's too short to deal with other people being cruel to you.
I shouldn't leave though. I'm not a fan of defeatist attitudes.
It's not defeatist to want to leave a group of jerks. It's a show of strength that you don't have to follow the crowd and would rather be a good person on your own than be one of a group of jerks. Do you want them to corrupt you with hateful feelings into being a jerk too?