Terrified

I was finally given a diagnosis after 7 weeks of what I can only describe as what feel La like a rollercoaster ride in the middle of a horror movie.They kept changing the decisions as to what was to be biopsies first, repeat biopsies, repeat scans etc before finally being diagnosed stage 3B NSCLC

Although I have just turned 70 I was until this diagnosis very fit with no other health issues.

I have been told combined radical radiotherapy and chemotherapy over a 4 week period is my best treatment option.

They used the word cure, however I realise that survival rates for this type of cancer are low, 20-30% over 5 years.

I am terrified that this combined treatment will leave me physically impaired and while of course I want to live, the quality of my life matters. 
I’m finding it so difficult to deal with my family’s emotional distress and I absolutely do not want to cause any more if I can help it.

Has anyone any advice?