Don't fret too much Jon this is very curable these days.
I went through it all over 10 years ago now. I found a lump which I didn't do anything about for months. It grew quickly so I bit the bullet and went to see the Doc. A week later I was lighter on one side
I then had the scans which showed it had spread to my lymph nodes down the side of my spine and like you this was the biggest shock. When you have you ball chopped of you think your fixed and when they tell you its spread inside then thats when it really hits you that you could die.
Anyway 4 sessions of chemo and a major operation later and I was fine. All in all it was 10 months of crap but I'm fit an healthy and have been for 10 years.
Chin up dude and put a brave face on, you'll soon be out the other side!
Paul