Is a girl considered disobedient to her father if she refuses to let him speak to her mother privately—knowing that her father has emotionally abused her mother, causing her illness—especially since the father has cursed her, does not fulfill his duties towards his family, and slanders the reputation of his daughters? And what is your guidance?

If your mother is still married to your father, you do not have the right to prevent him from being alone with his wife or speaking to her privately. Speaking to him harshly and roughly is a forbidden act of disobedience (uquq) and considered among the major sins. Allah Almighty says: "So do not say to them [i.e., your parents], 'Uff,' and do not repel them but speak to them a noble word" until His saying: "as they nurtured me when I was small." You must repent to Allah and appease your father, and obey him by visiting his second wife whenever possible, without harm. If he is neglectful or unjust towards your mother, advise him gently and politely, for the father's right is great and showing dutifulness to him is among the best deeds. The Lord's pleasure is in the father's pleasure, and His displeasure is in his displeasure, and the father is the middle gate of Paradise.