Sorry to hear this sad news friend. I can understand your confusion, pain, and even possible anger. My granfather was the source of my "being" as an individual and a human being, he was and is me. Truly when he died no one on earth mattered to me. Carry you memories and love for him deep within your heart, make him proud of you for the rest of your life. Memories are the mirrow of his life that you will always have. If your Gramma is still alive, be strong for her, but let me say too that tears are just a sign of inner love that come out at at times like this.
My condolences friend. - Jim