Is saying what's up my cracker racist if it's between two white people?

My niece on my inlaw's side who is black wrote "Grrr I hate racist people God is coming for your suckers" on FaceBook. But she didn't put that on her status until awhile after I wrote "wcrackin my cracker" to one of my white friends on FaceBook. At first I thought nothing of it, but then I made the connection and thought "what if that racist my niece was talking about is me", even though I'm not. But I don't know she might not have even been talking about me. Black people say n*gga all the time in relation to their own people. I show brotherly love to my white people as well, even though I have no problem with other ethnicities. Am I wrong for being that way?