You're entitled to be moody, so don't worry about it. For a couple of days, I was alternatively angry, apprehensive, anxious, sad, impatient and, amazingly, a little excited (to get it over with). My family doctor (who is a good friend) immediately offered Xanax, but I declined since I wanted to feel like I was in control of things. But if it helps you, I wouldn't hesitate to take it.
In the end, what sustained me was all of the research I had done that confirmed the safety of the procedure and the better outcome that awaited me "on the other side". Better health, less anxiety for me and my wife and kids, a comfort concerning my ability to lead an active life (I'm a runner who always knew my wife worried when I went out for a long one or ran in a race), and a general feeling of gratitude that my condition was treatable (even "fixable"). All of that made me feel better and, more importantly, helped me relax. In the end, my outcome has been fantastic (I'm running my first long distance race since December 2009 surgery, a half marathon, in May) and I'm grateful every day for everyone who made it possible. Betting you'll feel the same soon but, in the meantime, being moody is just a part of the gig. Enjoy it while you can.