fear only if its you she has the drop on
The one time I was in that situation I had to think through the fear--concentrate, because my body was reacting in a fight or flight mode, adrenalin rushing to extremities making me shake. Yet I had to have a good aim. I was able to do it because I had practiced the scenario and did not have to figure out what to do. I had it memorized.
Fortunately no firearms involved. A big unleashed dog attacked me (and my leashed cocker spaniel, a very macho breed.) and I maced the shit out of him. Pissed the owner off, so I told him to sue me or shut the fuck up. The law was on my side.