Can't stop crying Grandpa died a year ago?

My grandpa had hospice for the last 3 days he was home, (we lived with him) he had brain cancer and lung cancer, and all this, and my parents thought it would be good if i stayed with my other grandma while this happened, so i wouldn't see that. Then when i got the phone call he died, i felt nothing, i didn't cry. Nothing. When i got home i just layed under his bed, i needed to be near him. My mom thought i needed therapy or something because i didn't cry. So she sent me to my cousins (next door) and he talked to me, and i kinda wanted to cry, but i couldn't in front of him. Is that wrong? I couldn't i made myself not cry in front of my mom, because she has no parents, i can't imagine what thats like. And this happened in March 2008. Now i can't stop crying and bursting into tears. What's wrong with me? Why didn't i cry then? I feel like i should have spent more time with him, little things, said hi, watched baseball with him. and i feel so bad and this just adds to the tears.