I was told I now have Annixiety Disorder

Yesterday I took my first trip to my theropist.
She was surprisingly very nice. And listened extremely well, which I pictured she would since it is in fact her job. I told her all of my problems, and she explained to me that I have an Annixiety disorder.
Apparently it is when I get something so worked up, my stomach hurts, and everything ends up going all sjhyiuyeiophjdkhjsk. She said that it will go away after about 1,000 sessions. And apparently she has to have a few talks with my Step-mom and I because most of the problem is my step-mom.
I don't know if you all know of my step-sister. She does not live with me, she's a sophmore in college. But she's said some pretty mean remarks to my step-mom causing her to take all her anger out on me.
This morning I overheard my step-mom say; "she has to go" I immediatly panicked beings the fact my step-mom would be kicking me out but much to my surprise she didn't kick me out, my dad took me to school and told me everything would be fine.
I hope.
It seems like even if I forget to do one thing everything turns bad, and sour. I get yelled at and called a "spoiled brat" more times then I can count and then she says I can't live there anymore. That then upsets me, so I call my mom and doesn't listen, but still.
I have a feeling tonight is one of those nights where her anger will all come out on me. And there's nothing I or my dad can do about it.
I just have to sit there and listen to her yell and scream about how spoiled I am. And I have to say, it sucks because when you're being told by someone who should be your parent that you're a terrible person, and have absolutly no right to live on this earth, you kind of feel like you're a piece of crap.
All this was why I moved with my mom, but it didn't work out. I hate feeling this way. And I know I have depression and it's all because of her.
The stupid women I'm stuck with.
I wish it would all just go away, but it can't.
And on December 28th it will all be final.
My dad has no idea that most of my pain comes from her.
It sucks to know he will never know that he made my life a living hell because he married her.
I can't take any of this anymore, it's coming towards my breaking point.
And there's absolutly nothing I can do but sit and watch my world crumble down.
Talk to you all soon,
N.C.L.