What should i do? it is unfair?

the man had NO right pushing in when you were serving, how RUDE!.... however.. you do get customers like this, and working in customer services you have to be prepared to put up with this sort of behaviour, at the end of it, it will only make the customer look bad.. not you.. you have to remain calm and ignore them. you must never do something like that to a customer, he could get you into a lot of trouble, i know you say where you are from it works like that, but if you want to work in another country you have to understand and take time to know that it can be different, im afraid you may be in a lot of trouble no matter how angry you feel at a customer you must NEVER get physical.. if you remained calm something could have been done to prevent the customer coming back, however just by your silly actions you have completely turned the tables, i do hope things work out for you, but i think if you were my employee, i would have to sack you, or give you a serious warning, remember to always keep your calm if they want to be racist, let them go to hell