Do I really have to invite my brother for thanksgiving?
Well, why wouldn't you invite him?
Because our relationship is bad.
Your brother is a part of your family, and it's super rude to exclude him like this. He deserves to join in just as much as you do, and the holidays are a sign of unity and love where you can work out all your differences.
I can't work on it. I have to look out for me now.
Can you work on yourself and invite him over. Maybe you can set up some boundaries so that you get along. People will think you are being rude and maybe  not want to come to Thanksgiving.