There are police hotlines to report anti-social drivers. I think this is worth reporting just so their reg gets logged.
I think you have integrity. It's tough being a principled person confronted with thoughtless/aggressive behaviour. Ones instinct is to front up to it, but you then have to process the anger that can come from these things - and that can take time and have a bad effect on you.
I always try and weigh up whether it's worth it - and the impact it will have on people i'm with, but it's not easy for sure.
About a month ago i booked a night away at a fancy hotel for me and my wife on our wedding anniversary. When we got there the reception staff were rude and offhand. I was about to complain about their attitudes, but didn't want cause a fuss as it was a special occasion. My wife suddenly said "i'm not staying here to be insulted by this horrible sloan" and we turned hand-in-hand, exited the hotel, went for a pub meal and drove home. Couldn't have been more proud of her. That said, it's not always the case that she takes my side.