Was this wrong of me?

A long time ago it think when i was in 2nd grade (now im going to 8th grade) my grandmother passed away and i didnt really know her that well because she would hardly visit us since she lives in mexico, and she's is a little mean and strict but she is still nice to me sometimes, and that one day that i heard that she passed away i didnt even cry(i usually cry a lot, i am a crybaby)and im wasnt sad either. And my mom cried and then she asked me why im not sad and why i didnt cry and i had to lie and say that i was sad. And i feel terrible for not feeling that least bit sad that my own grandmother is gone and i dont feel any emotions for her not anger, not sad, not anything.And no matter how much i ask myself this, i dont know, so can someone plzzz help me i have been wondering this question for years. :(