The "N" word is an example of something that gets periodically bantered about in my house.
Now I can see why you were so upset. You would be justified in asking people who started talking like that in your home to either stop doing so or leave. You could also call them afterward and explain that they won't be invited back unless they stop talking like that.
Since you still want to maintain family relations, it may be safer to visit them than having them leave, since leaving a gathering early is less awkward than telling people to leave.
