When elementary school kids are more mature than a lot of us teens and adults, feels bad man lol.
Personally though, there should be a limit of you trying to reach out to someone and letting them hurt you. Like her brother, who refuses to change. I understand why she wants to reconcile though, he's her only family. And for a lot of people, blood relatives are important, or because of the bond they've spent before isn't easy to let go.
But there are times, you just have to. Someone has to change to move on一 either them or you. And you have to stop being there for them at one point if they so refuse to. That's why, I hope the brother apologizes and changes soon. It's hard to lose someone.