Remind yourself of this: you're the same person you were before your diagnosis. Whatever qualities your friends and family have always valued you for are still there.
It's natural to want to protect those you love from what you're experiencing - but the risk is that you'll get lonelier and those around you will feel excluded and robbed of the opportunity to show love and support. Secrets are a great burden, so share the load with those you care about. Tell them how you feel and how they can help. Talking about problems relieves anxiety. Don't try to go it alone.
It often helps to look at the past. Reminiscing is therapeutic and often helps when broaching sad and sensitive issues. Photos are reminders of good times long forgotten. Making sense of the past can help you accept an uncertain future.
Your friends and family may be feeling just as shocked, angry, sad and frightened as you are. This may make it hard to talk to them, but a family which communicates well is much more resilient and able to cope than a non-communicative and secretive family.