Hi Mat,
I'm sorry you had such a crappy experience at this job. I work full-time, but I don't think I could have handled your job--it sounded like a perfect storm of needing to be always on with evaluating eyes always on you and no support. I agree with others that the fine art of being a good boss or supervisor is one not practiced as widely as it should be, to put it politely, and that sort of thing can touch the most vulnerable parts of us. I hope you have another opportunity soon where you are properly respected and supported. I think the fact that you are willing to try so hard automatically makes you a good employee.