The emotional questions come before, not after. I'll give you a real-world example. So let's say that you are a leader of a group of Soldiers or Marines in Iraq, and your job is to drive down the same set of roads every day, looking for guys who emplace roadside bombs. There is a street corner that you pass every single day. And every single day, little kids throw rocks at you from this corner. This goes on for a period of a couple of weeks. Then, you get a tip that this corner will be used to throw an anti-tank grenade at you. This grenade has the capacity to kill everyone inside one of your vehicles, so if it happens, you will be responsible for about 4-5 widows or parents who lost their 19 y/o sons (or maybe both). You have a clear choice: You can either roll the dice, accepting whatever risk comes your way towards you or your men. Or you can open fire into the crowd of kids, ensuring that no one will be using that corner again to attack you. There are some important caveats: 1) Warning shots are a war crime. If you open fire without the intent to kill, you will be sent to jail, period, end of discussion. 2) The bad guys have the potential to win a propaganda victory no matter what. Either they get to video themselves killing Americans, showing that they are baddest guys around, or they get to claim that you are the Great Satan who kills kids. So, Leader, what do you do? Those are the questions that you have to answer before, not after the fact.
I don't know how many people or anything like that I have shot. It's not quite like a video game where you see them fall down in front of you. Sometimes, you see little puffs of smoke from a machine gun or AK-47 fire from the side of another hill. You and your guys shoot at what you can see, sometimes at shit you can't see. Anything that looks like it would be a good place to set up (places with good cover, etc), you shoot it. When you eventually make it over that way, sometimes, you see no dead bodies. Sometimes, you see a whole bunch of them. The latter is a good day, but no one knows who hit what. So how do you count that? Other times, you very clearly see what you're shooting at, and you definitely know when you're the one who shot the guy. It's whatever. You still don't feel bad about doing exactly what would be done to you if he had the chance.