You don't own the space at the rear. Your responsibility is with regard to the space in front. If there's no vehicle in front then there is no need to ease off or drive unpredictability. This doesn't excuse the other driver but pulling over would have been a far less antagonistic response.
this car is an embarrassment to the driving community. I saw this reg plate going high speed down a main road snorting a strange white powder off a key
Caught red handed parked on the bus stop