Bottling my emotions up?

So, my grandpa has cancer, anc doctors say he only has a few days to live. While my family is bursting out in tears, and upset, I feel emotionless. I'm trying to obsess about other important things trying to block it all out. Usually i tell people not to bottle up their emotions, but this time it's me. I feel saddened about my grandpa, and regret not spending more time with him. When will I let it all out? Why can't I just let it all go?