Whatever wealth you think you'll get from this (which isn't even close to a guarantee, as your investors are likely going to get paid before you), is it worth your kids growing up without a parent?
Apply to some corporate 9-5 jobs with good salaries and see what the decision looks like for you. It sounds like you're in a toxic and dangerous situation. These kinds of dysfunctional startup environments don't lead to big exits.
Based on these limited details, if I were your friend or relative, I would urge you to walk away from this company and take care of your family instead of your investors.
Either way, save yourself. I would suggest "practice yoga" but I don't think it'll help that much.
I remember back in 2007 I went to the emergency room of a hospital, unable to breathe. Stress has cause my stomach to bloat to such a degree that it was squeezing my lungs. The docs saw that I wasn't some junkie faking the pain to get strong prescription drugs. One doc (not more than 30-35yo) took me on the side and told me "whatever is stressing you, quit it now.. work, gf, affair, hobby, whatever THAT thing is.. stop it tonight, otherwise the pills won't save you" (btw I got the prescription but never bought the pills).
I get the exact same vibe from you. If the exit of that tunnel is within arm's reach, keep at it. My friendly suggestion is set a deadline (1 week? 1 month? but not more). If things are 75.0% with a positive outlook --> continue, if they are 74.9% or less --> pull that cord and eject.
5m in revenue should mean you could sell for a pretty penny.
I learned this the hard way a few years ago, when you have an opportunity to take a break, do it. Particularly after something's happens. In my case a "friend" ended up setting me up, but I still regret not taking my planned long term vacation.
I'm literally of the mindset right now that I'm done working for 3 months in either August, or earlier if I get fired.
To quote Bob Marley, Money can't buy Life
Investors don't owe you as they only risk a small sum of money in each investment and the risk is accepted.
There is a relevant book, "How to Stop Worrying and Start Living", that you can read between the therapy appointment and the next SPA/massage session.
If so, speak to your investors.
I wouldn’t frame it as you’re close to an heart attack. Say the workload you have hurts the company and that you need to hire someone who can deal with all those admin / operational things to run the company, so you can focus more on the product and accelerate growth.
Alternatively if you can cash out then consider that, if you think your health will deteriorate further and cause early death or make you partially paralysed (stroke).
Selling your house and car and moving your family to a more dangerous part of town is quite the gamble.
Take care of yourself and hope the gamble pays off.
Don’t buy into the startup hustle BS. Cash out. Spend time with your family.