- I think your wife needs to know. I have never taken a big decision like a job change without consulting my wife. We're in this together, and if I wanted to not have to share this decisions with someone else, I would have stayed single. Please don't take this as an attack, I am not judging you. I'm pretty sure you don't want her to know so you don't stress her, but you too are in this together, and there's no need for you to go through this problem alone.
- I think you may have a partial view of those jobs you mention. It's quite likely that a bagger at a grocery store does not suffer the stress you have at his or her job, but the pay is also much less, and the stress may come at other parts of life (for example, if that job forces him or her to live in a bad, dangerous neighborhood). Construction? working outside must be very hard in the middle of the winter or the summer, for example. I think it's good that you consider other options if being a founder is burning you out, but you don't need to go to the other extreme.
- You and your family are the ones to decide if quitting is a good option. Don't worry about the company in that case. You are entitled to pursue your own happiness, and people who work for startups (I know, I have) are or should be aware that failure is one of the options, usually the most likely one. So please don't feel like you need to put up with something that makes you supremely unhappy so that the company stays afloat.
So my summary is: Find what is best for you and your family, don't worry about the company if you really feel that unhappy, and if you do quit, if finances allow, take a short break and then don't go for the first thing that comes your way. You are smart enough to have started a company and getting it close to an acquisition. That's something I was never able to do, so I say 1) hats off to you, and 2) you won't have trouble finding a good job once you're ready to do that.
Good luck.