I quit at 53, single, but I actually just quit my job, so I didn't have quite the same decision to make as you have, though it wasn't easy. After a few months to get my head right, I started applying to some places, and a week later found out I had some windfall coming. So took the time dealing with that, once I figured out where that put my total holdings, and started running calculators. I gave myself a deadline, and when that time came I declared to myself that I was retired.
I was very solid on knowing my expenses (and they are loooow), I had spent that time unemployed figuring out insurance costs, figuring lumpy expenses, running models, I upgraded my basic spreadsheets to include more data and inflation, messed with the numbers a bunch, did tax form iterations, by hand, for future milestones to figure out exactly how cap gains, SS, RMDs, etc, would impacted my taxes, and then tweaked my spreadsheets some more. I basically decided that I might have to live pretty lean until I can start collecting SS. It was worth it to me. The stock market and interest rates went a little crazy right after that, so I'm doing a lot better than my worst case, now. Of course that could change at any time, but I remind myself often that a 50% loss in the stock market affecting what I have now leaves me about where I was when I decided I could make it work.