I'm so sorry you experienced such a toxic workplace. You did exactly what that workplace wanted---you quit. Then, they owe you nothing. Mind you, in an at-will state, you can be fired for just about anything (except for reasons that are against federal law).
Anyway, I don't really have much to add, but this bit of advice: ALWAYS keep a journal of every shift. I learned this the hard way when there was relentless bullying and harassment in my old place of employment. When we (there were a few of us as 'targets') were approached by management and asked for specific dates, times, co-workers involved, etc., I really couldn't remember many of the details to make a strong case.
I now keep notes on everything.