How do I get my friend to stop using the N-Word and her actually listen to me?

Let me preface this by saying that my friend doesn’t seem to be using the N-Word in a derogatory way. I’ve never thought of her as racist and I’m really disappointed. She NEVER cusses so this has shocked me.

My friend is white and so am I. My absolute best friend in the world is black and I don’t know what I would do without her. I’m not making this post to start anything, I just don’t know how to address her because I’ve tried and she won’t listen.

I absolutely hate when people use the N-Word and I noticed it sounded like she was saying it about a week ago but I gave her the benefit of the doubt and assumed she was saying something else and that I misheard her. She said the word about 10 times in a matter of 2-3 minutes. Today I was talking to her and she was calling her friends “n***a” and saying when she was on FaceTime she replaced the song lyrics “Little Do You Know” with “N***a Do You Know” and continued to sing her modified version. I’m in highschool and in that particular class there were less white people than black. I asked her MULTIPLE times not to say the word but every time she replied by saying that she wasn’t meaning it in a bad way but that she was just saying it. All of my friends in that class kept staring at her and giving her mean glances and so I continued to ask her to stop since I despise that word. I don’t think she understands that she shouldn’t say that word and I don’t think she sees anything wrong with it.

Do any of you guys have a way I could explain it to her easier to why she shouldn’t keep saying it? A lot of people were saying they were going to fight her if she kept saying it. I don’t want to drop her as a friend but I also don’t want to be associated with her while she’s using that word. I know the reasons to why she shouldn’t use it but I don’t think she really under and I need an easier way to explain it to her. Help?