As you say, it is an emergency. I don't think an examiner is going to care about whether you're scared or cry or what emotion you show as long as you "perform" correctly? Everyone is going to be scared/upset during an emergency.

I had my car stall at a light (big Mercury) and I put on my flashers and emergency brake, etc. and went back to the nearby gas station to call a tow truck (and I had a formal dinner to go to that I was late for so had to call my husband to come get me, etc. big mess) and while I'm at the gas station someone is enquiring does anyone know who the Mercury belongs to, etc. and I overhear and finally get connected with it. A little Toyota had not SEEN it stopped at the light, with flashers on, etc., still daylight, and had barrelled into it and pushed it (emergency brakes on and stalled) through the intersection! The emergency people couldn't find the driver of my car (obviously, since I was at the gas station :-) and were looking down in ditches along the side of the road, etc.

My car was totaled and a couple people in the little Toyota were taken to the hospital, etc. (and they had no auto insurance, of course) but I had been on the way home from my T when this happened. My T and I had to talk about it for several of my next sessions, how "calmly" I did things at the time but then fell apart and was crying, shaking, and the post trauma for me just driving by the site for a long time was through the roof! And I hadn't even been "there" when it happened. I kept expecting my new car to stall, someone to hit me, etc. My T explained that we're sort of built to deal with emergencies and to fall apart after they're over and it is "safe" to. But I can see how "practicing" them would be just like the real thing!