When I've felt that stressed about an upcoming event, I lived with a notebook and pen next to me at all times. When you wake in the middle of the night, or the stressful thoughts become intrusive, jot down what you need to not forget. Once a day (am is best, so you don't forget your early morning appointments) go through your notes and create today's list of things to work on (NOT necessarily things to get done, or to finish, just to work on) I often find that I've written one thing down repeatedly. That's the one that I make sure to do at least the next baby step on. And when you cross off the extras, the whole list looks much more manageable.
You'll get through it. Time doesn't stop, and then once you're done, you'll be able to look back and think that you'll never have to do that for the first time ever again!