If your bear a grudge against someone, and it doesn’t effect her, and you know that by talking to her it wouldn’t help, and its just a matter of time — what must you do before Rosh Hashanah?
The Torah instructs us not to “hate your brother in your heart,” and according to the Ramban this means that one must make sure that one speaks out one’s grudges, and not keep them in one’s heart. Bearing a grudge might also infringe the prohibition of Lo Sitor. Not every grudge is “hatred,” but if it cannot be spoken out with the other person involved, you should try to be as forgiving as possible, to see the other’s point of view, to know that whatever happened was directed from Above, and to focus on the positive for a positive start to the year — so that the grudge is uprooted from your heart (see Rambam, end of chap. 7 to Hilchos De’os).
Kesivah Vechasimah Tovah.