Have I turned into a monster?

I lived in Out of state for three years and then to Peru for another three years and while I was there my grandmother helped me a lot with advise and just someone to talk to, for it was very rough. I missed her so much and sometimes I just set and tried thinking I'll never see her again. I had no way back home and no money to talk to her as much as I wanted or needed to. So to move on I had to harden my heart and just work to make ends meet. Then in September she passed away so I came home in December thanks for my mom's help. Yesterday was my grandmother's b-day and my brother was devastated but yet I didn't feel a thing and to be honest I forgot!! It's like nothing seems to bother me any more, I want to blame it on all the hurt I went through and how I had to harden myself in order to work and not suffer. Now my family wants nothing to do with me because I have no feelings. it's like my heart doesn't change during crisis or lost of a loved one. BTW, she raised me and was much closer to me then my own mother. What can I do to suffer with my family in stead of being the only one that doesn't shed a tear? Sometimes I have to fake it. Please help. thanks.