Telling the boys

How to tell the boys (Zach is 14, Carter is 11)... The day after I got the diagnosis, Zach was going away snowboarding for 3 days. We decided to wait until he got back to tell them. Saturday afternoon - we are sitting around chatting, so I say 'I need to tell you guys something'. Zach immediately said 'I don't think I want to hear this' and tried to walk away. I told him to sit down and then I told them. Carter asked lots of questions, Zach got up and walked away half way through my answers. I had to let them deal with it in their own ways, that would be okay. We hadn't told any of our friends and family yet, we wanted to tell the boys first.