What must the questioner do after having falsely sworn to a person who threatened to harm his family, subsequent to that person intentionally colliding with his car then rubbing against it, causing scratches, and the questioner retaliated in kind?

Lying is one of the great sins, and it is permissible in three cases: reconciling people, war, and a man's conversation with his wife and a woman's with her husband. Scholars have appended to this what is necessitated by dire necessity or urgent need to save a Muslim's life, property, or honor. If a person fears harm to himself and his family, and he swears falsely, we hope that he is excused. It is incumbent upon one who swears falsely as a precaution to offer expiation for breaking an oath. As for damaging the car, the two damages must be assessed; if they are equal, there is nothing, but if they are not equal, then each owes the other according to the extent of the damage.