A father forcing his son to keep his wife in the house without visiting her family

Q: I am a young man in my thirties and I am currently doing my post-graduate studies at the faculty of medicine. I have been brought up by my father and I was renowned for being very dutiful and kind to him; all praise be to Allah Alone. When I was in the first year of my undergraduate study my father married me, upon my will, to my cousin (the daughter of my father's sister) whom he loved and respected very much. This happened six years ago. During the first years of my marriage my wife and I were outside the country as I was studying abroad. When we came for a short visit after one year of leaving the country, I allowed my wife to spend most of the time with her parents. Unfortunately, this made my father angry. He tried to convince my wife that what she did was wrong but I told him that she acted according to my permission. My father then tried to convince me to prevent my wife from staying for long at her parents' house. I tried to satisfy him without displeasing my wife but in vain; he asked me (Part No. 25; Page No. 148) to divorce my wife. However, I told him that Allah (Exalted be He) made peace between us and he changed his mind after I had begged him and kissed his feet. Time passed quickly as we were still abroad. Petty problems would repeat whenever we went on a vacation and visit our country. Allah (Exalted be He) granted me a daughter but this increased my Father's discontent. However, my wife is now in the seventh month of another pregnancy. It is worth mentioning that my wife is dutiful to Allah then to me, all praise be to Allah for choosing for me such a wife. Nevertheless, something recently happened that I did not expect. My father told me strange things about my wife's family. He thought that they use these things against him and that they are his enemies. He cut all ties with his sister. He asked me to divorce my wife and he wrote a long letter to tell me that he will be angry with me, consider me an undutiful son, and make Du`a' (supplication) to Allah not to grant me success in the affairs of my marriage and children if I do not obey him. My father then mentioned the story of Prophet Ibrahim and his son Isma`il (peace be upon them both) when the former asked the latter to divorce his wife and he did so to obey his father. Respected shaykh, what do I have to do now? I am happy with my marriage; all praise be to Allah Alone. I have a daughter and another child is expected to come soon. I am pleased with my wife's character and she performs all her religious duties. She did not commit any thing wrong to be divorced. On the other hand, my father threatens that if I do not divorce my wife he will be angry with me and will make Du`a' against me. How can I deal with such a difficult situation?In conclusion, Will I be considered disobedient to my father if I refuse to divorce my wife? Will the Du`a' mentioned above have a bad influence on me? (Part No. 25; Page No. 149) It may be worth mentioning that I decided to continue showing my father my willingness to please him and to remain in contact with him while ignoring the issue of his request. Please give me a clear Fatwa that may be a means for satisfying all of us.