How would you handle the embarrassment of starting a new job six months pregnant?

I recently landed an excellent job that I have been interviewing for for two months. I hid my pregnancy through all of my interviews. I beat out many other strong candidates for the position. I start work tomorrow and it is undeniable now that I am pregnant. I am embarrassed to show up. I am normally a very confident person. But now I'm doubting myself on many levels. I don't want to be a disappointment to my superior and a joke in the office. I am tempted to walk away from the position, though I need the money.