Taken for granted

This here is my six year old sister whom I love so so much and cannot live without. I would do anything to be able to spend as much time with her as possible and see her grow. Unfortunately, i was recently kicked out by moms current boyfriend and disowned by my mother. She never raised me and always blamed her past for never learning to be a mother. I was forced to move in with her at age 11, young, optimistic, and loving my mother as much as I could to feel accepted and loved by her. Tomorrow I turn 21, that relationship I always wished and prayed to god to have with my mom has never happened. Nor will ever happen. The thing is, she chooses men over her daughters. The current boyfriend disrespected me in front of my mom and furiously kicked me out because I was "trying to parent my little sister when I am not the parent". I yelled at the top of my lungs asking my mom why would she ever allow a man to disrespect and destroy the little family (me, my lil sis and mom) apart. She too, encouraged me to get the f*** out because I was an adult and not her problem anymore. For 11 years living with her, I wished nothing but to be loved and cherished by my mother. Sadly, I figured out in those 11 years that I was nothing more than just a problem to her. More like a burden since I have a personality and she didn't like that. She always treated me so foul and came home everyday from work taking out all her frustrations on me. Now that she's being financially secured by the new asshole boyfriend she can do whatever she wants. That includes being a shitty parent to my little sister, and still having sex with other random guys. That's why my little sisters dad dumped my mom and kicked us out of his house. Now I feel like she is only doing the same steps and is going to put my little sister in uneasy situations the way she did me. I will be 21 tomorrow and a piece of me is sad to know that growing up really does suck. And it will only get more difficult in time but not once have I given up who I am, happy. So don't ever lose hope in whatever situation you may be in. I will know I can never have a mother but that's okay. I have many strong, beautiful, loving women around me whom have helped me not lose myself.