So this person (white male, early 20s) who I have had classes with in high school and now college and with whom I am friends on Facebook has recently taken to saying the n word ("my nigga" [about another white male]). Yesterday I messaged him asking him to maybe rethink how he approaches and uses the word, citing a) just because you're white doesn't mean you get to do whatever you want. I got this reply:

I understand your feelings, and that you want the world to be a better place, and you want social justice and all those things, cuz hey, I want that stuff too. But I have to say, I was a little offended that, as my friend, you wanted to change the way I talk. I understand tho, but I'm sorry, even after reading your feminism article, I still am going to say nigga. I refuse to be afraid of a word, and I hold a differing opinion concerning it, much of it based on my personal interactions with the African-Americans in my life. I know you wanna change the world, but you gotta accept me girl.

How do I respond? Should I respond? What's a girl to do in situations like these?