Hi Shireen,
I can't really add much to what's been said, other than teenagers are often quite robust and too focused on their own relationships to worry too much about their parents problems. My own 'natural children' were in their 20's when I was diagnosed, and my teenage step-children were still getting over the angst that I had had the temerity to marry their mother, so perhaps it was easier in my case.
What I have noticed with my wife, is that she needs to know that I am open and honest with her, if she thinks that I am trying to spare her bad news, like a high PSA result, then her imagination goes into overdrive. So I have learned to tell her everything she wants to know.
You may need to focus a little on your own wellbeing, many of the wives on this site have talked about anticipatory bereavement, by the sound of it your husband has many years of life ahead of him, and they may be many years of worry for you. I don't know quite how you combat that, it seems a bit flippant to run out the mantra that 'I've got cancer but cancer hasn't got me'.
When I was first diagnosed I was desperately keen to learn all I could, my wife and I used to go to all of my local support group meetings, and our house was full of reading material I had picked up here and there. Slowly but surely we have got rid of all references to cancer in the bookcase and I know longer go to meetings, I can keep up-to-date on the Internet and find this site very useful, but my wife and family can get on with their lives without constant reminders that I have cancer.
I am not saying that is the answer, and I don't suppose a day goes past when my wife doesn't suffer some anticipatory grief, but it seems the least we can do to make our lives as normal as possible, and yes we do have some fun, and yes I do sometimes forget that I have cancer.
:)
Dave