My heart goes out to you. Most of us don't understand how the gravity of your diagnosis. You must feel like you've been kicked in the gut and your mind must be aswirl. The emotional support of those close to you will help but knowledge is key to reduce your well placed anxiety. Start by reading: Understanding Melanoma: What You Need to Know by Perry Robins; MD and Maritza Perez; MD, which will answer many of your questions and debunk many myths.
The next few months scans, endless bloodwork, and other diagnostic tests will be depressing reminders that you may be seriously ill. On the otherhand, you may not. Do whatever you can do to take of the things that you can take care of.
Be brave but reject foolish bravado. Act gracefully although you're afraid. Be mindfull of the stress that your health will place on those who love you. Support them as best you can; it will be good for you.