Wow...I feel so bad for you. Don't ever think that things will never get better for you, because I've been in the blackest of black holes and somehow was lifted out of it.
Maybe it's hard to believe but, I've felt the same things that you do most of my life. Even though I'm a guy I've been physically abused by my father and other bullys since I can remember. I was also sexually abused by my former doctor. All the feelings you have of shame and worthlessness are mine too.
I'm just writing this to show you are not alone. You can find people like me, that sadly understand what you're going through.
Can I give you any advice? The truth is that advice can't change the past. What we both need is a way to cope with the future. Maybe writing here is a step in the right direction...for both of us.
Take care...rcguy