Sick and Tired of being treated like a teenager

I quit my job because of the passive-agressive stance the employer took to managing the office, and I was tired of being treated like I knew nothing, and was just there to dust the furniture.
I am a grown-ass woman, with talents and abilities, and I do not appriciate being treated like a highschool student, and given menial labor.
I wanted to scream at the boss that I am 28 years old, please treat me like an adult, I have proven to be resourcefull and efficient, yet you keep treating me like I am not qualified to perfom the simplist of tasks.
I was fine on my own for a week when M went on vaction, but now that she is back, you are back to treating me like SHIT!!!
WHAT THE F---?!?!?!?!

But I didnt do that, I sent a politely worded e-mail to the boss lady - and a politely worded, but some what snide e-mail to M, who went and showed it to the boss, who was quite unpleasent to me then.
What a bitch. Both of them.
I was nothing but calm, kind, courteous and that was how I was repaid. Stabbed in the back.
People Suck.
I am tired of trying to please them, I do what I want. Not for you, for me, and I am not going to ever put myself in such a disrespectful situation again, I am one of a kind, irriplacable, and if you do not feel that way, you can just politely decline to hire me, I wont care.