Hi, Kim! It sounds like you're anxious about returning to work because you haven't worked for awhile. Also it sounds like there's alot at stake ($$, pride) and you're afraid of messing up and losing your job. I don't blame you for feeling that way. Starting a new job is stressful for anyone, depressed or not. Anxiety about making a good impression, learning the job duties, meeting new people, fear that you won't do well enough, etc. is enough to make a person implode. That's perfectly normal. Remember that your new employer wants you there, so obviously they think you have the skills to do the job, good work ethic and the personality to fit in and work well with other employees. And you were selected over a whole bunch of other qualified candidates and in this awful economy! So there's something about you that's really, really good....
Good luck on your first day. I'm sure you'll do well, because you care about the job. Let us know how it goes.