Naruto: Itachi 'Rain'

The final battle of Brother Uchiha, it's the most tragedy..
I try to recall and give a best answer to myself, why this happened, but nothing can do. (355-359)
When Sasuke called the fire ball to struggle, the only thing he saw was revenage, the only thing in mind was send his dear brother to grave.
I turst that Itachi was cried many times when he's alone.
We all know his young brother was his live, but that's why the tragedy happened. T_T