Oh I hear what your saying, and I didn't intend to be insensitive. However, to just quit your job because you don't like it or makes you feel sick kinda bugs me. Then my tax dollars will likely pay for you to sit on your ass for a few months while others work hard who equally hate their job as much.
There are plenty of other options. Like take extended time off, see a therapist, find a hobby to take your mind off of things.
Working 12 hour days could be hard on anyone, especially a stressful job. This only works for people who live for their job, which most people don't. There are too many unknown factors here to really give a good opinion, but it's better to find work elsewhere than to stick with a job that could possibly kill you.