I wish you luck -- these circumstances are ver difficult, and they can destroy your health. Run, don't walk away.
Seriously, don't wait, you are shortening your life by accepting that sort of phantom stress. You have skills, you are not trapped in this job by anything other than your desire to carry through with things you started and your fear of change.
I don't mean to start any flame language wars but am a bit curious what sort of language / platform you are working with. In my experience, companies that build their products with dynamic languages (not strongly typed, etc) tend to play things a bit more "fast and loose" and the workload can really pile up. They usually don't know about best practices like test drive development, etc and don't care, even when this is pointed out. This led me to steer my career towards working with a strongly typed, compiled language (I do server-side web dev) and, at least with my current job, I have noticed a much more refreshing approach as far as professional development practices compared to other jobs where dynamic languages were used.
Unfortunately there are many idiots in the workplace, and that translates to many bad workplaces. ( Office Space Dilbert etc are not funny because they're off the wall; they're uncomfortably close to real life.) But don't let this put you off from leaving. No-one should be put in the situation that you're in.
You could try adjusting work / life balance:- get more exercise, drink much less caffeine, get a self-help book or course about dealing with stress and use those techniques at work (and remember, it's just a job), remember to take regular time-outs (you're using a monitor, so you should be having at least 5 minutes every hour), don't get pressured to do silly hours, etc etc.
FWIW I have a lot of sympathy for you. Bad working environments suck, and suck hard. Employers need to learn that treating the workforce humanely is in the best interest of their business.
Possibly not relevant to you but: In the UK your employer owes you a legal duty to protect you from stress in the workplace.
The duty is clearly defined in law, and has been tested by the courts and employment tribunal many many times.
But - so what? You need to be able to turn that protection into something that helps you.
Seek advice; and then gather evidence of what things are too stressful, and if anything could be done to reduce that to a manageable level. Then go see a line manager and ask to talk. Present these things, and see if you can work something out. Realise that you probably can't, but at least you now have some protection if you decide to leave.