Should Racial Slurs Be Accepted or Permitted

I usually post on Fridays but Essence has a hot topic about a White man who calls his Black wife racial slurs during intimate moments.  Many readers feel the letter is a fake.  Others feel the woman is getting what she deserves and many are voicing disdained.  I on the other hand am keeping mouth shut until I give the matter some thought; however, I am taking a poll to see when it is permissible for racial slurs to enter into a conversation, if ever.