James L. Kugel and Rowan A. Greer, Early Biblical Interpretation, ed. Wayne A. Meeks (Philadelphia: Westminster, 1986) 92.
Indeed, it is as if Ben Sira has read all three parts of Lev. 19:17 as a single exhortation: You shall not hate your brother in your heart, but instead you shall surely reproach your neighbor, so that you shall bear no sin because of him. Open reproach heads off anger and hatred--as he later observes (Ecclus. 20:2)--and thus protects the offended party as well. In sum, Ben Sira's message [in Ecclus. 19:13-17] is: Reproach your fellow for all the good reasons I have stated: because reproach may prove that the offense in question never was committed, or because it may at least prevent a recurrence of the offense, or because reproach may show the offense to have been done unintentionally. And even if none of these be the case, you still ought to reproach him to avoid being guilty of sinning against him. Then, as to his offense, "Let the Torah of the Most High take its course," which may mean "Divine justice will take care of itself" (cf. Rom. 12:19), or, again as we shall see, let further legal proceedings, ordained in the Torah, then take place.
I came across some of these ideas in my weekly quiet time, for which I was studying II Samuel 13. David's eldest son Amnon rapes his half-sister Tamar, and Tamar's brother Absalom says nothing to Amnon for two full years. Absalom then invites Amnon to a sheep-shearing festival and has him killed there. Matthew Henry notes: [Absalom] said nothing to Amnon of this matter, either good or bad, appeared as if he did not know it, and maintained towards him his usual civility, only waiting for a fair opportunity to do him a mischief. That malice is the worst, [w]hich is hidden closely, and has no vent given to it. If Absalom had reasoned the matter with Amnon, he might have convinced him of his sin and brought him to repentance; but, saying nothing, Amnon's heart was hardened, and his own more and more embittered against him; therefore rebuking our neighbour is opposed to hating him in our hearts, Lev. xix. 17.
Kugel shows that Jewish interpreters tended to apply Leviticus 19:17 to judicial matters rather than mere slights: if an Israelite transgressed the law and deserved legal punishment, then his fellow Israelite had an obligation to rebuke him in hope that he'd repent.
But Leviticus 19:17 and its interpretation may offer a lot of wisdom about how to handle slights. If we confront a person with his offense against us, good things can happen. We're giving vent to our anger. We're allowing the offender to apologize or explain why he did what he did. We can understand his perspective better and see that he may have problems himself. And we may even learn that he didn't mean to hurt us.
Or bad things can happen. We can confront him and he won't apologize. Maybe us venting our anger will add gasoline to the fire. Perhaps I talk to the guilty party, and our resentments run so deep that reconciliation does not occur. Or he'll throw in my face my own moral shortcomings. Or I may be too shy to confront him. Or I can "reconcile" with a person and still not feel comfortable around him. It's a tough call!
Something helpful my AA sponsor once told me: We ourselves have to decide if we can live with an offense or something annoying. If we can't, then we'll have to confront the person. But we'll need to be ready to take the consequences of the confrontation, whatever they may be.