[Warning: This story contains vernacular language and violence]
He thought he was alone.
Itachi killed them all and left him suffering alone.
But little did he knew that he wasn't the last one of his clan (that he loves), nor that Itachi was not as cold hearted as everyone thought.
He would soon find the person that he loved most in this world was alive and he would protect her with his life.
Sasuke will find his baby sister.
Just remember that nothing lasts for ever, not even happiness.