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Sigh family dilemma halp

Hey guys c:
Well i just had this massive argument with my family and heres what happened:

My Mum drove me down to Burger King and this car cut our lane, HE gave my Mum the finger and my mum gave it back and mouthed some words
So here's when the stuff went down. It was raining so we decided to go drive through, then that previous car came up to ours, rolled down his window and started shouting 'WTF IS YOUR PROBLEM UGLY &^#$%? GET THE &$^@ OUT OF THIS COUNTRY"(we're Asian) etc.. So yeah my Mum rolled down my window and using her limited vocabulary of swear words, shouted back.
Basically I just rolled my window up after they shouted for like 10 seconds and told my mum to drop it and forget it. My mum then started getting angry at me for not arguing with her and then told me we should of called the police etc..

TOO LONG GIMME SUMMARY: angry man shouted at my mum, what should i have done?

Soo basil what should have I done? My dad told me to ask my friends online who's opinion was correct.
(Me) Just forgetting it and drive away.
(Dad) keep arguing and if worse come then call the police.

Please give serious answers just this once Basil
I really just wanna prove my dad his thoughts are wrong.