Can I file a lawsuit against my boss and company for not responding to an obvious toxic situation?

I have been working under a boss that told me to do things that were against company policy, unethical, immoral and even illegal. I contacted her boss and hr to let them know about this. They said they would take care of it, but did nothing. I contacted them several times to request a transfer. I was under great emotional distress and was usually crying when I contacted them. They told me they would look into a transfer and would give me a call back. They never did. This situation caused me such mental and emotional distress that I began to have physical problems. It ended with my having to go to a mental institution. The health insurance I have through this employer is company run, and they are now refusing to pay for my stay at the institution, even though I was pre-approved. Do I have any recourse against my boss, her boss, hr or the company?