http://revach.net/article.php?id=4762

Section: Halacha   Category: Tshuvos
Chavas Ya'ir: Asking Mechila When Your Friend Returned The Insult

The Chida says that if you do not ask your friend Mechila before Yom Kippur, not only is that aveira not forgiven but neither are any of your aveiros that you have committed Bein Adam LaMakom.

What happens if you did something to your friend but he cursed you out in return, must you still ask him for Mechila?  The Chavas Ya'ir in his Sefer Mekor Chaim says that you must still ask for Mechila.  There is a difference however in the degree of Mechila that you must seek.  If your friend answered your attack in kind then if you buy him and Aliya and after the Aliya he says "Shkoi'ach", that is considered Mechila.  However if he did not counterattack when you wronged him, then Mechila like that would not help and you are obligated to personally go over to him and apologize and hope he forgives you.

Another very important point brought in the Piskei Tshuvos (606:1) is that even if you friend is angry at you unjustly, still you must ask for Mechila before Yom Kippur.

Important Note: We bring this tshuvah as a starting point for discussion and not to convey any halacha.  We try to convey the Tshuva to the best of our ability. We admit that our understanding may not be accurate. One should learn the tshuva to verify the accuracy of our interpretation.  Please understand that this Tshuva may not be the final word on this topic. One should consult a Rav before drawing any conclusions.