Praise be to Allah the Lord of the Worlds.
We advise you to dialogue with your parents and avoid conflicting with them because you seem determined to marry that particular woman your parents may have a good reason for rejecting her as they are experienced enough to judge that she isn`t suitable for you. However, marrying that woman is your choice not theirs. From an Islamic viewpoint, none has the right to prohibit you from marrying a certain girl or compel you to marry one, but we don`t recommend having conflict and discord with your parents at the start of your marital life.
As for your father`s oath to divorce your mother, he is required to personally check with the Iftaa` Department to see about that. And Allah the Almighty Knows Best.