Am I obligated to divorce my wife after the death of my father, who ordered me to do so, knowing that she is pregnant and I have not informed her of my internal decision to divorce her? And would my not divorcing her before my father's death be considered an act of disobedience?

A man is not obligated to divorce his wife if his parents command him to do so without a legitimate Sharia (definition) reason, and this refusal is not considered an act of disobedience (ʿUqūq). If the man utters the words of divorce, then the divorce has occurred. He may take his wife back if it was the first or second divorce and as long as she is still within her waiting period (ʿIddah). However, if his intention was to divorce without uttering the words, then the divorce does not occur, and his wife remains his.