What is the ruling of Islamic law regarding a wife who asked her husband to watch pornographic films, and was then divorced, but denied the reason for the divorce and falsely accused her husband?

Divorce takes effect regardless of its cause. The wife's request to see her unmarriageable kin (mahram) in this manner is forbidden (haram), and it is unlawful for you to comply with her in that; rather, you must prevent her and show protective jealousy over her. Her accusation against you and your dispute with her family do not entail a religious ruling if they are baseless. You can take your wife back as long as she is within her waiting period ('iddah), based on Allah's saying: "And their husbands have a greater right to take them back in that [period]." You must be keen on the welfare of the children, for the parents' togetherness is more conducive to their proper upbringing.