So I was recently diagnosed with polycythemia and the doctors words were literally "holy fuck! They didn’t tell you this 7 years ago???

I’m having a very hard time right now because people with this condition are expected to only survive 20 years after the diagnoses. Meaning I have less than 15 years to live. I’ll never see my child graduate high school. I’ll never see them get married. I’ll never get to meet my grandchildren… this sucks. I’m so terrified right now. What am I supposed to tell my wife? What am I supposed to tell my parents? I’m going to die before all of them? How did I upset the universe to deserve this? I’m so scared and I don’t know what to do. L