Cancer destroyed my life twice

Not sure why am I writing here.  Feels like it might help just to tell it to someone.  Mostly there are good days when I am ready to give it my best fight.  Sometimes I have bad days when I see no point in doing anything.  It's one of really bad ones today

I am only 32.  My wife died of cancer 7 years ago.  We only had a week after the wedding and before the diagnosis.  It broke me.  I never had a romantic relationship since then, endured in a lot of drinking, even dropped all of my hobbies.  Luckily I managed to at least start getting my life back on track.  I am a scientist.  I managed to radically change my field of research and started a PhD in medical physics 3 years ago.  My work is on cancer X-ray diagnostics method.

I really don't understand how people can have normal life.  Get married, get a place, have children then grandchildren.  My life is totally different.  5 months ago I myself was diagnosed with stage 4 melanoma.  In most likelyhood I will not survive for more that a year.  

I'm not scared of dying.  To be honest, I felt worse when my wife was ill.  It's just makes me angry that I wasn't given enough time to make a difference.  And my mom...  The hardest thing which I had to do in my life was telling my wife's mother that her daughter passed away.  I can still vividly remember my walk from the bedroom where I received the call to the living room where my mother-in-law was at a time.

I don't know if my mother will be able to cope with my death.  It will destroy her like it once destroyed me.  And that makes me insanely angry...