I was in a very similar situation (nasty commute, 3 years of very stressful work with a lot of hours). I left without a job lined up. It took me less than a mo

I was in a very similar situation (nasty commute, 3 years of very stressful work with a lot of hours). I left without a job lined up. It took me less than a month to find a new job that I liked. I had several offers and declined a number of them early on as I looked for something better. You can certainly do it. I suggest you take two weeks off to relax and prepare for interviews, then hit interviews hard and keep practicing for whiteboard interviews.