I react in the actual moment. I have an example the other day - coming down a straight road, slight downhill so maintaining just over 25 mph, in primary. Up ahead a car is waiting to pull out, checks, see me and decides 'its only a bike and pulls out'. Luckily I'd seen it coming, seen no traffic coming towards me or junctions on my right, so I simply yelled "NOOOO!" as I pulled into the opposite lane and overtook.
I didn't need to shout - this was already part of my planned response when I had seen the car, but I did so simply in anger at the stupid move. It was a female driver that visibly jumped as I yelled. I then noticed she didn't pass me but hang well back, even when we both later turned off onto a second road.
I've also once paid a visit in uniform to a driver that left hooked me, which to this day is still the nearest moment I've had to being knocked off.
However, I don't like the idea of stopping and remonstrating, simply because I'm concerned if the drivers an arse and wants to get physical. Whilst I am relatively confident in a physical confrontation, I've always been a bit more concerned about starting one whilst astride a bike, wearing cleats. I'm sure an angry driver won't allow me the courtesy of gently putting my bike down safely!