I have seen a lot of people die. It's all like a big blur really, you can not make sense of it and things swirl around in your head for a while. After some time things settle down.
I don't have nightmares or any post post traumatic issues. I get a little "edgy" in stressful situations at home or at work but other then that I don't have any problems. There is nothing to really dwell on, you do what you have to do and then move on. I don't spend any time on "what if" it is pointless.
I can say this; if the time comes to and it is between my life or someone else.... well I won't think twice about it. Life is too short as it is, what is in the past is in the past.