My dad been going crazy, what should I do?

Being a police officer, it is my oppinion that your father speak with a therapist about his problems but he may not care and may not want to. If anyone is to sugest this to him, it should be your mother not you or your sister. When he gets angry like this, throws things, breaks things, and if he ever threatens any of you again, especially if he threatens to kill, the police need to be called and they will deal with the situation.