Why does my bio mom hate me? Why am I not good enough for her family?

My bio mom gave me up for adoption when I was born and my adoption hasn't been that good. My adoptive dad and mom divorced a little bit after my adoption and I never saw him after I was 1. My mom then started dating a bunch of guys that would beat her (and sometimes me) and she would go on and off prescription drugs to deal with the pain. I'm 17 and I currently live with a friend of my mom's but honestly, she could care less about me. She's only letting me live here because my mom just recently got arrested. I found out 3 years ago from my mom who my bio parents were (it was a personally adoption not through an agency) and a year ago I finally got the courage to call my bio mom. I explained to her who I was and she said she wanted to meet me. I thought this will be the chance to finally have a mother that loves me. When I met her, we talked about each other's lives and I found out she's married to my bio dad and that I have 3 sisters and a brother. When I asked if I could meet them, she told me no. She then told me that she didn't want anything to do with me. I didn't understand. I asked her why and she said "because I gave you up a long time ago......forever and I want you to stay gone". I was so upset. I asked why she gave me up and she said at that point in her life she wasn't ready for a child, not that she was underage, or poor, or coerced or any reason that I've always imagined why I was given up. I was so angry. I told her she should have gotten an abortion instead then I went into detail about how much my life sucked because of my adoption. She then said "That's terrible but that's not my problem, its yours. I thought they were nice people" then she left. I called multiple times everyday demanding to know more. How can someone say something like that? After a week, I finally got in contact with my bio dad and he offered to explain the whole situation to me. I thought he sounded nice, but what he had to tell me made me feel so much worse. My parents gave me away to strangers mind you that they were: 24 years old, out of college, had good paying jobs, their own place, their own things, and were married. I wanted to die. His excuse? "We just weren't ready". My little sister is 2 years younger than me. What the hell could have happened in 2 years to magically make them ready? I feel so depressed. I've tried to reach out to them, to get to know my siblings but they ignore my calls and letters, and my bio mom sent me a Facebook message saying "you need to stop harassing my family before I call the cops". Her family? Aren't they my family too? I just don't matter to anyone. I don't understand why they did this to me. I don't care what any of you pro-lifers say, I'd rather have been aborted than to live with this pain inside of me.