Keep your chin up, because it's not the end of the world. No one is immune to riding out a failing start-up; I've seen really bright and highly qualified engineers, who have just relocated their families to a new city, fall victim to a failing start-up. You have very marketable skills and will be able to find a new job faster than most people in other industries. Your CEO will beg you not to leave, and will have other employees guilt-trip you, but you need to figure out how long you want to go unpaid before leaving and stick to that threshold.

The funny thing is that you may find yourself in this same situation with another company in the future. It's a common game that start-up CEOs play and the faster you catch on for next time, the more control you have over the continuity of your employment and income. I.e. don't be afraid to cash your last paycheck and quit the very next day, without 2 weeks notice.