Its very sad to know about your father my friend. May his soul RIP and courage be with you all to go through these difficult times. I can understand what you are going through but life and death is a cycle and whoever comes has to go, it is inevitable.
I know your mind is in a very different state, but I want to tell you that your father will always be with you, it's just that he is now not in the physical body, but his presence will always be around and you will not be able to feel this presence in grief. Too much grief will not allow him to reach out to you all, hence remember him in happy times and happy moments you spent with him. Life is a learning experience for all, you will learn many lessons with his loss and that will help you elevate at your soul level.
Be peaceful and in a state of calmness and you will feel your father's presence around.
Best wishes for you and your family my friend. Stay strong :-)
One of my very close friend passed away so suddenly around 6 months back, we are still not able to come to terms that he is not around, life is such, very unpredictable, you do not know what will happen next. Live life every moment happily with yourself and with others.