['My grandma died 15 years ago this week.  I really miss her.', "That's so sad. Did she live a happy and fulfilled life?", 'Yeah she lived to be about 55.  We always used to love going to her house for Christmas!']
That's so nice! Perhaps you should dwell on good memories like that of her to rid yourself of your sadness. We have to remember the good times with our loved ones!
I really miss my grandma