My son’s classmate said the N word

My son’s classmate said the N word to a Black student. My son didn’t know what the word meant but contextually realized something very serious and wrong happened. It bothered him for a while because he told me 2 weeks after the fact on a car ride. I have emailed the teacher and guidance counselor. Should I tell my son to stay away from this child? She has used bad language in the past and been physical. I don’t know what exactly is going on with this child. Should I be doing more? They are in 1st grade so they are still learning social skills and self control.