The responsibility of carrying is mind blowing.
The reality of knowing that carrying alone makes me realize that by having it, my whole world of decisions in a what to do cases change dramatically because of my responsibility and i can see how scary that can be.
Furthermore to the op, I know a woman personally who owned a gun, became a victim of a home invasion, failed to shoot and her own gun was taken and she was shot as a result, with her own gun.
Seriously consider your choice to carry if you have to think about using it even if to defend someone else. The last thing you would want to happen is for one of your own to have died in a situation you described and that the stranger that was carrying never fired. Even more, say he only fired and saved the life of himself and his family while he allowed your son or daughter to die first.
I can't sugar coat this any more than i already have and no one can make you put your life on the line for a stranger, but in my eyes if you think you are better than a stranger when you value yourself more and that is something that none of us can change .....character.