I was like you, at the end of my rope. Just could not take it any longer and I started looking and if I got a response or asked to test while working, I logged off. It took a few tries before I found another job and I quit on the spot.
Like that one post stated; they would let you go in a heartbeat and could care less. Take care of yourself, your livelihood, your sanity, whatever, and find something else and quit.
BTW, when I got the "you can never work for MM again w/o notice" I laughed. That is exactly why I quit on the spot. Who in their right mind would ever want to work for this place which is truly h3ll on earth all the way to outer space.