I think that most of us understand that spitting in ones face does not justify use of lethal force.
After reading some posts and a bit of retrospect I have something to add. I have seen countless posts where members preach about use of force by civilians. Some responses here are quite interesting about what would happen if someone spit in your face! What if you're carrying? Do you respond with escalating force while armed? You've just made use of your firearm quite hard to defend in court. Now is the time to stand by your convictions and call the police and be a good witness. Your decision to go armed has limited your ability to respond with escalated force as some would argue although spitting could be assault, its not life threatening.