Will I ever have a mother?

I was adopted at 2 weeks of age. My adoptive family told me as soon as I could understand what adoption was, so I have known my entire life. I've experienced many emotions over the years including anger and hurt. My adoptive mother was emotionally abusive for most of my childhood. I was compared to other children in the neighborhood or children of her friends, and I think her biggest concern was how others would view her if I didn't match up. I recall her threatening to abandon me if I did not do as she wished. She would get into the car, drive around the block, and return home. This was very traumatic for me as a young child. Her behavior was so unpredictable and as I got older I became convinced she had a type of untreated mental illness. My adoptive father was the silent partner. He did nothing to stop my mother's abuse, but I can't say for sure that he even recognized it as a problem. There was a time when I was in middle and high school that I was angry with my birth mother and wished she'd have had an abortion. As I got older came to realize she did not choose the family I was given to, and I redirected my anger to whomever determined them to be suitable parents. In 2005-2006 I searched for my birth parents. My father immediately signed off on releasing his identity to me, but my mother refused. In my state the law allows the release of both birth parents' identity or neither, so my mother had made the decision for my father and me. I received a letter from my birth mother indicating she was married and had 3 younger daughters. Her husband was aware of my existence but her daughters were not. She refused to release her identity in an effort to protect her daughters. I quickly realized she was not protecting anyone but herself, and her selfish behavior was preventing me from knowing my birth father. Why I am somehow less of a daughter to her than my 3 younger half sisters I will never understand. I am quite sure she gave birth to all of us. Had she been honest with her other children from the beginning, she would not be in this position now. I feel I am the one paying for her choices. My adoptive father and I now have a positive relationship. We became closer once I was in college. However, I have very minimal contact with my adoptive mother. It's sometimes difficult to keep in touch with Dad when he and Mom are married and living under the same roof.