How do I proceed when an employer allows workplace harassment and sabotage?

I have been documenting almost 6 months worth of harrassment, sabotage and bullying from what I can only determine to be an "industrial psychopath". She is so toxic that she is involving other employees in her mission to get me to quit. This is a small gym with an owner who has no ability to handle this situation. There is no HR department. I have repeatedly tried to resolve the situation through rational discourse, but the situation continues to escalate. We are each considered to be independent contractors, but are micromanaged and treated as employees. There is a complete breakdown of communication and the turnover rate is rampant due to a toxic bully and an incompetent business owner. I could say a lot more; this is only the tip of the iceberg. The easy action to take is to move on, however, I've witnessed one individual run many others out of this gym and I'm beyond livid. Any advice would be greatly appreciated. Thank You.