I'm so sorry you lost half your hours. That has to be really scary in this economy. I'm hoping it all works out for the best for you over the long run, even though it might seem terribly unfair right now. I mean, the job sounds like it's pretty bad for you, health wise.
In all honesty I am struggling with similar issues. The last two full time jobs I held were horribly stressful and fast-paced--both were in call centers. I did that kind of work for eight years and then had what looked like a heart attack at my desk in 2008. It turned out to be an anxiety attack, but the ER bills came anyway and boy were they doozies.
I quit shortly thereafter and have never regretted it, yet work remains a problem for me, and now the economy is horrible and that doesn't help at all. I have a part-time retail job and do some 1099 work online, but have constant guilt that I don't make more money. Plus, it's not cheap to have mental health issues. I just got out of a psychiatric hospital on the 28th and dread those bills--our out of pocket limit is $4 k and who has that? Not us!
So many employers are mildly to openly abusivee right now, and the productivity demands of even bad jobs today tend to be off the chart. It's hard for people WITHOUT mental health issues, never mind people who struggle even under the best of circumstances. These are not the best of circumstances. So I guess I'm saying, don't beat yourself up. It's rough out there all the way around right now.
I wish you all the best and hope your therapist and/or psychiatrist can work with you to get you into a better situation somehow.
My retail job is mildly abusive but I try to just ignore the supervisors and smile and nod. I mean, they pay so poorly, I figure if I just keep showing up that's 90% more than most of their employees do, and so far so good. But it's hard.