>>718898959
>How did Snake overcome his admiration for The Boss to kill her?
He thought she really was a traitor at the time.
>The title of Big Boss felt undeserved
Yes, exactly. It's a title that he despises more than anything because it's an albatross around his neck that he murdered his own mentor without realizing she was only acting a role from the start. It's only later that he finds out she was actually a plant all along. When he salutes her grave at the end, Big Boss knows the full truth and is a broken man.