The cousin's wife and daughters

Q 1: I would like to tell your Eminence that my father died when I was one year old. Then my mother married my father's cousin. It was his aim to marry her to raise my elder brothers and I. He brought us up very well. May Allah reward him with the best. After that he had five sons and two daughters from my mother. In 1406 A.H., he married another wife and had two sons and a daughter from her. I lived with him in the same house because I regarded him like a father. After I married, I lived in a separate house. I thank Allah because I used to treat him very well. I attribute my good education and position to Allah's Grace then to the help of that man. After that in 24/12/1412 A.H., he died in a car accident. My brothers and I were working in the city of Tabuk. He (my father's cousin) was a military man in Tabuk. After he retired, he returned to the city of Al-Ta'if. We could not return with him to Al-Ta'if because it was difficult to do so. After he died, I demanded (Part No. 17; Page No. 435) to be moved to the city of Al-Ta'if to take care of my mother and my younger brothers. I also wanted to show my gratitude to that man by caring for his young children. My request was accepted and I thank Allah for that. My question now is: Is it permissible for me to see the wife of my father's cousin during the period of mourning? It should be noted that I used to see her in the presence of my mother; because I regard her like a mother because it was her husband who brought me up. Is it permissible for me to marry her to take care of her children? I fear that her father who lives in the desert may take her to live with him, which will negatively affect the children and they may not be brought up well. Is it permissible for me to see the daughter of my father's cousin or not?