Original
Breathe. Don't panic. Read up on everything you can. Find good suppports - I'm part of a wonderful ITP group for my country (my initial disgnosis). They've been very supportive. Be willing to ask for help and support. Regardless of your illness, live your life purposefully and meaningfully. Accept that you'll probably experience a whole cascade of difficult emotions and make room for them.
I think I've coped with this thing as well as anyone could. I'm very lucky in a way because my career is all about helping people to cope with pretty awful things and so I knew what I could do that might help me through.