Yes, it is difficult to react with normality or kindness to a person who is seriously unpleasant to us, and much more so when we can harm others, but we must use a courtesy that is not confused with hypocrisy but that does not bring us closer to what those same people represent.
Let us always show our best version with seriousness and respect to those uncomfortable and not compatible with our character to project that we want and demand the same treatment.