Is a wife's speech to her husband about harm inflicted upon her by his relatives considered backbiting, or is it in the category of stating the truth or confiding in her sister with a guarantee of confidentiality?

Backbiting is forbidden and considered a grave sin. However, scholars have identified six instances where it is permissible. One of these is when someone who has been wronged seeks justice, based on the Almighty's saying: "Allah does not like the public utterance of evil, except by one who has been wronged." Al-Kamal summarized these exceptions in the following lines of poetry: "Slander is not backbiting in six cases: one who seeks justice, one who introduces [someone], one who warns, one who reveals an iniquity, one who seeks a legal ruling, and one who seeks help in removing an evil." Therefore, there is no blame on someone who backbites those who wronged them through words and deeds by mentioning the injustice inflicted upon them.