How should a young man act towards his father who practices homosexuality and watches pornographic films, and has relationships with maids, while fearing the destruction of the family should his mother find out?

If what you mentioned about your father concerning illicit relationships and watching pornography is confirmed, then you must seek wisdom and Allah's help, and frequently supplicate for his guidance and for his situation to be rectified, while keeping the matter confidential and not informing anyone about it. Then, gently and kindly advise him and remind him of Allah, and warn him of Allah's punishment and the disgrace, scandal, and fragmentation that would afflict the family if the news spreads. We advise you to observe piety and patience, for this is a trial whose outcome will be good for those who are pious and patient, in accordance with the Almighty's saying: "Indeed, he who fears Allah and is patient, then indeed, Allah does not allow to be lost the reward of those who do good."