Is it permissible for a committed Muslim to expose someone who wronged him, with information that would harm them, in retaliation for that injustice?

It is recommended to pardon and forgive those who wrong you, seeking Allah's reward, for the recompense is of the same kind as the deed. The Quranic verses and Prophetic traditions have praised forgiveness and those who forgive people.

If one does not wish to forgive, it is permissible to defend oneself by retaliating against the wrongdoing in a similar manner, without exceeding justice or resorting to falsehood. This is based on the principle of equal retaliation mentioned in the Quran.

The statement of Allah, "Allah does not like the public utterance of evil, except by one who has been wronged," has been interpreted as a permission for the wronged person to supplicate against the one who wronged them, or to retaliate in kind without fabrication.

Ibn al-Arabi explained that if someone attacks your honor, you may take their honor to the extent of what they said about you, but without lying. Do not respond to a sin with a sin. If they lied about you by saying, "O adulterer!" then you may say, "O liar! O false witness!" but not "O adulterer!" for then you would be a liar and a sinner.