Kids should definitely be free to "report" if they are being bullied or mistreated. However, this kid seems to report every little thing. The other kids are justified in not wanting to invite him. His mom should work on modifying his behavior instead of screaming because she didn't get her way.
I don't think I our a jerk but you do have major problems. Forgiveness is not for the benefit of the person who did the wrong. Forgiveness is for the person who was wronged. You have let this one incident ruin your entire life. Get counseling. Your brother and fiancée were jerks. They took chunk out of your life. But you are giving them the rest. Stop feeling sorry for yourself and take back control of your own life. I think you should go see your brother. You don't have to forgive him but you need to listen to what he wants to say. Sooner or later we all have to answer for what we do on this earth. If you don't go see your brother, I think k you will regret it later.