Does feeling the pain of injustice and being unable to forget what a friend did truly mean not forgiving her, and what is the way to calm oneself until her injustice becomes clear to her?

The woman did well by honoring her friend and bringing joy to her, and then by forgiving her. She will receive a great reward, for the Prophet, peace and blessings be upon him, said: "The most beloved of people to Allah Almighty are those most beneficial to people, and the most beloved of deeds to Allah Almighty is a joy you bring to a Muslim... And whoever suppresses his rage... Allah will fill his heart with hope on the Day of Resurrection." Forgiveness is to forgo accountability, and it does not negate the persistence of some impact in the soul, whereas overlooking (al-safh) is to remove the effect of the wrongdoing. Among the things that help with overlooking is pondering the great reward. Allah Almighty said: "And let them pardon and overlook. Do you not prefer that Allah should forgive you?" And the Prophet, peace and blessings be upon him, said: "Allah does not increase a servant by his forgiveness except in honor."