When a driver becomes angry or aggressive during your commute you may feel the need to react in some way, but keep in mind that this is often what they are hoping for. Just like the bully on the playground, they will only pick on people that react in some way.
The best thing to do is hold you line and do your best to ignore the driver. If their actions are enough to make you feel physically threatened, you can get their license plate and report them to the authorities. While this may not have a huge impact, it’s the best way to handle the situation.
At all times remember you are the slowest and most vulnerable vehicle on the road and, while we have a right to the pavement, we must keep a defensive mindset and do our best not to provoke anger even when we are in the right.