How can I get to go to the high school I want?

My situation is I'm going out with someone from my old school. My parents don't like that I'm going out with this person, and therefore have forced me to change schools. I used to go to a liberal public school where I didn't feel out of the ordinary. My parents transferred me to a private christian school, and I absolutely hate it. All I want is to be able to live my life in peace, and not have my parents control this aspect of my life. They are strong on their decision and there is no sign of them changing their minds. It seems like a minor problem, but I'm severely depressed and have attempted suicide. My parents don't see that all problems would be avoided if they would only let me do what I want. They have done everything they know to "help", but so far it has only made it worse. They have taken away all forms of communication with my old friends and I am currently seeing a therapist. I have done everything I know to get them to allow me to go back to my school, and now I don't care about anything and my actions are lead only by my desperation to see my partner. Now I am near hopeless, and all I know is that I can hardly bear this new school. Everyone I've talked to is either no help or only disappoints me. Please, I am desperate for help.