Heyy Katie.
I'm so sorry to hear all of what you're going through. Losing people is always hard to cope with, but could you spend some time with him while you can? just to try and regain the father daughter relationship and know that you were there for him. there's always time to try with people, and it might help you in the end.
Again, i'm sorry to hear what you're going through. feel free to
PM me if you ever need to talk, i'm always willing to listen. Keep strong.
Best wishes to you and your family diring this hard time. x