Drop them!
Your first concern is your husband and the racist comment was apparently aimed at him.
The wife has apparently neither apologised nor said anything in your hearing to her husband about his remark.
If she asks why you have cooled towards her be honest, and tell her that you value the help they gave when you were having difficulties, but you neither will, nor can, put up with racist remarks.
Have you even unknowingly put your foot in it?


