wow... tell me about it.
I was in your very same situation when I was 14 but things got pretty ugly for me, again, I feel like I screwed many things up, but now I feel like i have another one last chance for this... I'm not gonna let it go that easy...
I agree with what Shelly told you, and to be honest, just be yourself and be cool to your parents (cool in a way to keep things relaxed, without fights, trust me it's gonna help you a LOT).
Prepare yourself mentally, because this is just the beginning, these were your parents... society can be worse but I believe that when you are happy, nothing else matters.
Even if your parents help you only with therapy, take good advantage of it and BE HONEST to the therapist NO MATTER WHAT! ok? (lol I sounded like Mr. Mackey xD), she's practically the only person right now who can give you a hand and help you through this, even to change your parents attitude about your situation... so you want her on your side.
so... buckle your seatbelt Sammy... because Kansas... is going bye-bye
good luck on this... enjoy it, it's gonna be a huge roller coaster!