My parents are overbearing, how do I keep calm and continue to respect them?

I'll be 29 next year, I'm still at home. I am a school teacher but not full time employed. My parents particularly my father has always been controlling and dominant and doesn't like change. My mother's heart is in the right place but she wants me to be a perfectionist like her.My mother just told my father I joined a new private health care fund. They talk about me behind my back but in earshot of me. My father is furious and said I was bloody daft. They want me to stay with the same fund they have . I have wantd out for ten years but my mother has always disuaded me saying I have this and that to pay. I already pay all my own bills and manage fine.They would be furious if I ever moved out and rented without consulting them.Their contolling behaviour almost drove me to suicide when I was 14. I want out, what is the first move I need to do?Even with their own lives they make so many wrong choices and fall flat but never have allowed me to make mistakes & want me to be perfect.