I'm sorry you are going through that. Remember, you are worthy of do much more. You don't deserve to be told any of that, you are a worthy, strong, and beautiful human being. You've been told by too many people otherwise. Try to have respect for yourself, you are not anything they say to you. You a re good enough, you are more than enough. You are 17, almost 18. You've dealt with people tell you that for 17 years. In one more year you can go be whoever you want to be, and make something of yourself that shows them otherwise. Stay strong, I'm here for you if you need anything.

I'm sorry you are going through that. I have struggled with self harming for 15 years and do it in more ways than I realized, including self sabotaging, and still struggle with it to this day. What I work on is loving myself the way I wasn't loved when I was younger. Realizing that I have to be my own parent, my own love, my own comfort, and realizing that I am good enough just the way that I am. Self harm happens when we can't deal with the emotions inside, so we harm ourselves physically so we can deal with it outwardly and it takes the focus off what we originally couldn't deal with. I never learned how to handle emotions. My mom was always just telling me to get over it or was all over the place emotionally, herself. I just never learned how to deal with those things and I never learned how to love myself. People can say really hurtful things whenever they don't know what to do or when they feel like you are doing something wrong. It is actually called a persecutor, when some acts like they are okay and you aren't. It is called a victim when someone says I'm not okay, but you are or I'm not okay and your not okay. The rescuer is someone who says I'm okay and you're not okay so I'm going to fix you. The point is to get to the place of I'm okay and you're okay. It isn't enough to forgive the people who have hurt you, especially sexual abuse. Remember though, that you are good enough and that it was never your fault. Have you forgiven yourself for what happened to you? You are beautiful and you are enough.

You're surrounded by such negative people.
I'm going to give you my opinion, you may do what you please with it.
I'm not going to sit here and tell you not to cut. I'm not a hypocrite. I've cut since I was 14, I'm 23 and I cut again yesterday. Logically, we both know it's not right. But, neither of us can help it sometimes. Feelings are nowhere near logical.
This may seem silly. But, at times when I get the urge to cut, I color. I put all my focus into what I'm coloring. You may even, as well, write. There's a place here to write, or grab a book, or a scrap of paper you can burn or destroy once you're done with it in order to keep it private.

As for the people surrounding you, telling you that you're not good enough.. Those are toxic relationships. If I was in your situation, I'd absolutely try to remove as many toxic relationships as possible. Friends that say you aren't good enough aren't friends at all. If you're at school, wouldn't sitting alone with a good book be better than being with people who don't see your value?
As for your family, you're stuck there, I assume. But, don't see it as being stuck, see it as a lesson. Grow from their mistakes. I assume you'll never treat someone the way they treat you. Hold on to that. Perhaps find a job, meet people. Your life is full of endless possibilities. You just need to make them happen.
I promise you, you're more than good enough, and your life is valuable.
Your living, your breathing is part of something spectacular. You just need to find it.

If ever you need to talk, feel free to message me.
Have a good day