You hold responsibility for your own account, NOT somebody else. This would have been easily prevented if you had only taken simple measures to protect YOUR account.
I just went back to the site of the grief and I still found areas of broken blocks, although it still was a mess from other players as well. The original owner of the place called me in to check out the grief, and one of the names that showed up was yours.
It's a good thing your brother has his own account now, so that seems to be a bit of a relief, and I'm willing to let the ban go since it has been a long time. However, I still want you to pay close attention to the rules so that we don't end up crossing paths to the appeals again.
Much has changed, so please do prepare for a new world. Unbanned.