Will I be sinful if I refuse to affirm the validity of a sale that took place under duress, and I sold the apartment for less than its cost, before the court?

The jurists have agreed that whoever is coerced into selling his property has the option to either uphold or annul the sale. Coercion is established if it originates from someone capable of carrying out their threat, such as a ruler or a thief, and the fear of the threat being realized is overwhelming. The jurists from the four schools of thought (Hanafi, Maliki, Shafi'i, and Hanbali) mentioned that a sale resulting from coercion is not binding upon the coerced party, or is not valid, unless the coerced party ratifies it after the coercion has ceased. Therefore, if you were coerced into selling and have not ratified it, you have the right to request annulment and revoke the sale judicially, and the judge is the one who rules on the claim of coercion.