It’s funny that you used this post, because you completely glossed over one of the most important points in that post:
Welcome to the serious security risks. Now, Blizzard has to sort out whether you were exploiting, or your brother was. Now, they have to determine who was the cause and who was the effect.
You’ve made their job much, much harder, and quite frankly, this is EXACTLY why it’s not allowed. Do they understand family circumstances, and wanting to enjoy the game together? Absolutely, and they don’t go looking for these issues or laying down a banhammer. They tend to help people do it the right way, so they don’t lose years of progress.
But in these circumstances? It might not end well for the account. This is something you’re going to have to understand as you head down the appeal path.