yes. If I wasn't sure he was trying to kill me I'd try to maim instead of kill.
You better educate yourself about your state laws.
ETA: In most states, juries use the “reasonable person” standard to determine guilt or innocence. Would a reasonable person in the same circumstances fire their weapon? We’re talking the totality of circumstances here. Considerations include your age, weight, height, sex, physical health and life experience; the bad guy(s) age, height, sex, appearance and actions; the type of threat (weapons?); the reason for the threat (robbery? rape? knockout game?). The exact situation as it unfolded: who, what, when, where and why. Everything. All of it.