Do you feel guilty all the times about everything in your life?

I feel guilty when I'm with my family, because my father is a smoker and he is old and I'm thinking that he is going to be sick and die and my mother had heart problems and a smoker too and I'm afraid they gonna get sick and die, and I feel guilty because my dog is old too and keep thinking about dying and how I'm going to live when they are dead, this guilt feeling is torturing me, is that normal or is it just OCD? What should I do? Can SSRI help me?