Just because you hear a non-Black American person using slang, and saying Nigga doesn't make them "down". Get your children out of that frame of mind, and don't serve it up to the others who have yet to embrace these disrespectful anti-Black Americans.
Anyone calling you out of your name is being disrespectful and racist, they aren't friends they're White Supremacists or minions of their demonic system. Don't let them use "Nigga", that's just as bad as Nigger, I don't give a fuck who doesn't like it.
Tell them to use a term that's disrespectful to their people, don't use one that's disrespectful to you.
Everyone isn't built the same, so I won't tell you to just bust them in their damn mouth, but tell them to use disrespectful terms that offend them. They only play with people they don't fear, you don't have to be the biggest and you don't have to fight in order to conjure fear. If you know how to fuck someone up legally, financially, or in the public eye those are also useful tools.
I'm adding a news clip to this post as a prime example of why you can't play with the devil's kin or their minions. To hell with their excuses, and to hell with pulling punches.
This wasn't a group of Black men doing this to Black women the way so many articles try to paint us within the community. These were White Supremacists going after a Black woman making her life hell and taking food out of her mouth by making it hard for her to even stomach working a shift with them. You saw what happened when she didn't play the game, they let her go, I see similar in Hollywood and in the non-Black Media.