Second the Elance (or third, whatever). It's hard to compete with the third-worlders there, but man - you're starting from nothing. You should be able to double your income in your off time.

As soon as you're making $500 a week - which will really not be a problem on Elance for anybody competent with a good grasp of the English language - quit. Just walk out the door. No notice, just at the end of the day, go to your boss and say, "I'll be leaving now."

Then tell him your new hourly rate for consulting. Make it a good one. If you're as indispensable as you sound, you'll be working the same job with a reasonable rate within a few weeks.