I'm going to exclude my coworker from lunch break activities
Why would you exclude her?
I'm getting bored of her always complaining and bothering us.
It's rude to exclude someone from social gatherings at work, and it can be harmful to the other person's success.  If they are constantly dragging down the conversation, try to steer the topics away from things that upset her, or gently tell her that you are trying to enjoy yourselves.
Yay we can hang out with people I want to, and not with a loser who is annoying all the time.
I just think you should give your coworker another chance.