TREAT OTHERS AS YOU WANT TO BE TREATED!!!!!!!!

I am have been working at my current job for maybe about four years and I love what I do. But working in customer services you come across a lot of different personalities. For the whole four years I have been working in financial aid I never encounter the personality I did when a guy approached my window. I was working with a student a the time he approach the window. The guy: Excuse me I have a question, Me: I am working with another student right now I will be with you in a second, The guy but I am on the phone with FAFSA(Free Application for Student Aid), Me okay I will be with you in a second. Now the issue arose when the guy insisted on becoming very loud and rude. When someone else became available to help him instead of dealing with his business he needed to take care of he wanted to talk about me and say how rude I was for not helping him. Then he called me the N-word and yes he was African American now I was not mad that he used the N word but the fact that he called me a name. Now I feel if you come to a place of business you should conduct your business in a professional manner but he did not and when he called me a name I thought that the personal helping him would cease speaking with him and call security but she did not instead she let that student go on. Now my question is I am I wrong for feeling this way, feeling that security should have been called? Talk to let me know.