If what you say about the product is true, I'd strongly suggest you hold out just a bit longer than you want to. You may put yourself in a situation where other people get rich off of your labor, and you get nothing because you bailed (again, assuming the product is that good).

It sounds like you have a sales problem. Find someone really good at sales and try to get them to join the effort. Sales cures all, and it'll give you the 9 to 5 income, and slightly more regular hours, that I'm guessing you'd like to see coming in. With sales you can delegate some more of the labor that's crushing you.

Also, if your product is stellar, you can probably raise serious venture capital and accomplish the same thing until you get sales up.

It's often said that people tend to give up right before they get to the finish line. I happen to agree with that. Being a successful entrepreneur usually involves being able to endure pain that other people can't or won't, making it possible to stay in the fight long enough to succeed.

The task is to balance this equation: hang on longer than you feel like you can, but not so long that you do permanent damage (monetary, mental, physical, relationship, whatever type) you can't recover from. Getting that right gives you the best shot at success and limits the risk of regret.

If you're really, really, really certain your heart isn't in it, then bail in a way that perhaps enables you to retain a stake in the venture long term, and try to leave it in good hands.