Slurs are not just mean sounding names.
You have not hurt anyone's feelings by saying them.
It is not like calling someone "stupid" or a "bastard."
Someone being upset upon hearing a slur is not being overly sensitive nor are they overreacting.
Slurs dehumanize.
Slurs can make the minority individual feel as if violence TOWARDS them is about to break out. In most cases violence usually does follow after slurs get thrown around so there is a fucking good reason the fight/flight response gets triggered here.
Slurs automatically negate any sense of value. You are not human you are just...one of "them"
Slurs can be triggering, especially if someone has faced racially motivated violence before.
Don't use them.
Don't make fucking pathetic excuses for them.