Maybe you should just quit for the sake of your family. I am not being defeatist, or else just work out some milestones that you'll obtain from here onward. If you don't meet them, then quit.
Quitting is not an option and even ridiculous to me. I dunno if its the founder optimism at work but I am sure this is gonna play out great after launch. We are just 6 months into the startup and have yet to release our v1.0 with the iphone / android app. (ETA 2 months). Its tough but not impossible.
1- launching is always later than envisaged 2- you won't strike it rich on day 1 of release 3- doing something else on the side might actually make you more productive on your own project
Just don't crash and burn yourself. I'm a contractor and I work after hours. I rake a very decent hourly rate and I work my own hours.