My father is dying and I feel nothing at all?

My parents have been divorced for over 10 years and I haven't seen him for a long time; and only when I entered university did he want anything to do with me. He has a habit of making promises and then going back on them and he does not accept my sister who has special needs and now he wants to tell us that he is dying (I found out from a family friend weeks before) and we are not supposed to know. When I found out I felt absolutely nothing and I still do not. I am not sad, angry, resentful; I almost feel happy. Is there something wrong with me?