You need to visit a doctor and have your depression and suicidal tendencies documented. Quitting your job can exclude you from unemployment. If you can't take it, start looking for another job. Jobs are scare these days.
I would be very surprised if a lawyer could prove job related depression. I'd be more surprised if you could find one to take the case. Of course in this economy a job is a job. Wait.. Was that my phone? Lighten up.