I'll make this clear, you shouldn't be using the n-word on the server, discord etc. Regardless of if it's using the hard r or a it's not allowed on the server. What you say around people in your private time is up to you, but there's no need to be saying it in a public space for everyone to see (ooc chat, server voice chat, discord etc).
You clearly used the word maliciously and your attitude towards the staff involved after you were banned also doesn't help the situation. Your ban will be reduced to the original length of 3 days.