I am so sorry to hear of the sudden loss of your Dad. It's so awful when someone dies so suddenly like that. All the questions as to 'why them' and 'why now' ...... it's normal to think that way, and to feel so numb and so shocked.
I have lost a number of people in my life whom I loved, and one of the hardest was when my best friend was killed in a car accident. That was back in 1991 and she was just 22 years young. To this very day I can still remember getting the phone call. I had no idea how I would ever 'get over' losing her. But I've come to realise that 'getting over it' is not the right term. Well, not for me anyway. I think it's better to say that I slowly learned to build my life around this 'new' life I now had to face without my best friend at my side.
I also lost my Mum in 2012 to cancer. And I still have days when I want to call her and share my news with her. She too was my best best friend, and even though she was sick and I knew her death was imminent, I still went into shock and numbness.It's like your whole world has stopped, and you can't believe why people would still be doing things like talking and driving and just doing the day-to-day life stuff. It's like you want the whole world to STOP right there with you, and just help you to breathe in and out, because all of a sudden it hurts to breathe.
The only thing I can suggest is to just take it moment by moment. And if all you can do is breathe in and out, then just do that. It's gonna take quite some time to get used to not having him around. Be extra gentle with yourself, and don't let anyone put any kind of 'time limit' on your grief. It takes what it takes.
Perhaps you could write your Dad a letter and take it to his graveside and read it out to him? Do you think that might help? After all, his spirit will be forever alive in your heart. It's his body that is gone, but his soul is a part of you and always will be.
Anyway, in the meantime you can come back here as much as you like, for as long as you need to.
Take care. I'll be thinking of you. xo