What should we do about a father who wronged us, expelled his son and wife from the home, tried to get his son into trouble, and then cursed us and our children?

The most important recommendation regarding a father-in-law who behaves poorly is to be patient with him, pray for his guidance and repentance, and advise him kindly through someone he respects. There is no harm in a son avoiding his father to shield himself from his harm, provided he still honors him and maintains ties of kinship appropriately. A father's prayer against his children is forbidden by Islamic law and will not be answered, especially if it involves sin or severing ties of kinship.