Boy. this took a turn. OP was asking about using the word NI**ER.

Plain and simple, it is and has been for a long time an absolute no-no. Top of any list.

If you remember the movie "The Wanderers" back in the late70s/early 80s.
Italian gang leader in class getting into a beef with the black gang leader.
Back and forth they went with all the racially charged insults.
Until the Italian guy dropped the N bomb. That was it, time to rumble.

Gay slurs, other minorities slurs (wet-back, camel jockey) etc. etc. aren`t in the same ball park.