Castle Law only applies if you are in your home, not if you think you are in your home. She killed a man while in the commission of another crime (trespassing), she is lucky her situation is not worse.
(c) A person who has a right to be present at the location where the deadly force is used, who has not provoked the person against whom the deadly force is used, and who is not engaged in criminal activity at the time the deadly force is used is not required to retreat before using deadly force as described by this section.
A metric shitload of defenses goes out the window since she had no right to be present at the location.
She was not trespassing. No notice was given, and she believed she was in her own home.
I agree that she had no right to be in that man's apartment. But, considering the circumstances, murder seems too harsh.