Definately not my area of expertise to comment on how to deal with such a situation but the discussion did bring to mind something Col. Jeff Cooper wrote over ten years ago...
"The point is however, that winning a gunfight is not so much a matter of marksmanship as of mindset..." "To maintain control under conditions of lethal stress calls for a warrior mentality, and that is something that cannot be simply inserted into a police officer (me-or anyone else for that matter...) in the course of a training session."
Cooper's Corner, July 1997
And again in September 1997 he emphasized this same point in a response to the North Hollywood shootout in LA that year. Cooper's response to the insistance that the LAPD was 'undergunned' was "Now as we all know, one is only undergunned if he misses". His point being, I believe, that if you have that 'warrior' mindset your training will take over and you WILL hit to your point of aim or close to it. He also mentioned teaching students the Mozambique drill-2 shots to the chest and 1 to the head as a regular part of training. Certainly a well executed drill against an armor wearing thug would be over in three shots using such a method.
No matter what one's opinion may be of the Colonel's wisdom, you have to admit that "mindset" and "accuracy" certainly are key to coming out on the winning side!
I brought this up because of the question regarding the effect of 'killing' someone in a gunfight. I know I'm not the only one who has noticed that we have pretty much been 'breeding' violence out of our young people for at least two generations. What I mean is we just about have them convinced via the public school classroom that violence NEVER solves anything and "two wrongs don't make a right". God only knows the amount of time spent in Military training so our Warriors can get past this and onto the job of protecting our nation.
Unfortunately, we are fighting an uphill battle to counter-teach our sons and daughters that on this side of Heaven at least, violence IS THE SOLUTION to much (maybe even most?) of what is wrong in our world.
I made it a point to constantly remind my daughters that there is Righteous violence and there is unrighteous violence and what the difference is.
Sorry for rambling...