Prisons Are For Criminals

I'm a prisoner in my own house. I can't go anywhere because I'm only 17 and there isn't really anywhere TO go.. But I want out.
I want away from my dad. I hate him. He may have forgotten the fights we had and all the horrible things he's said, but I haven't. He's accused me of stealing money from him - like I'm just that horrible of a person. He always picks fights with me - and it's only started back up after S moved in. Like he has some point to prove.
He doesn't know what I am going through. He hasn't seen the self harm, and I'm glad.
But part of me wishes I could shove them in his face and make him see what he does. What he's contributed to. Not that he'd give two shits. I mean, why should he? He never has before.
But I'm so tired of feeling like an outcast. He likes S's son more than he likes me. I've seen it. I'm nobody. I'm the person in the family that nobody wants. And I don't want to be here either.
I wish I could leave.
I'm pretty sure S has seen the thinspiration poster on the back of my door. It makes me so nervous every time she comes into my room, there's so many things around that she can notice. My dad is too oblivious, so I never had to worry about it before she got here.
And I refuse to take any of it down, because this is MY room. MY space.
But she thinks she owns everything. She's mostly nice, don't get me wrong. But sometimes she oversteps her boundaries. Like how she always makes me eat dinner. Which I can usually fix with laxatives. If only I could purge.
I WANT OUT. I don't want to be around here with all these idiots that don't respect me or my lifestyle!! Not everybody has to eat as much as they do!!! They're just trying to ruin my life. I hate them. All of them. I want them to go away, forever. I have no interest in giving a shit about them, or getting to know S better. I don't want an f'ing mother. I had 2, both were cunts. I hate that word, but in this case, it's appropriate.
I don't want to be a prisoner anymore!! Just leave me alone!!