I was in a similar position years ago in a garage. Forced to work 13 days on 1 day off cash in hand or else I could leave. I left eventually suffering from burnout due to overwork. Nowadays though I'd be building a concrete case using film and I'd have them!
Is that person actually that bright. Nobody would get away with making you work 6 month straight no tribunal would find against you. Also in this day and age smart phones have cameras, you can shame arseholes on social media. She did neither - why?
Toxic people are everywhere. I would like to add that cannabis is legal in Canada. All of a sudden, there seems to be fewer toxic people around.