Before becoming a nurse, I was in behavioral health. My last job in that field dealt very heavily with foster children, and my previous two jobs did as well, only to a lesser extent. I understand on a limited scope the challenges that presents, though I have never been in your shoes and could never truly understand. But I am glad you have a father who was there for you and made efforts to make things work, even with the challenges he faced. But your mother's lack of involvement is indeed sad. I don't blame you for not wanting to be involved with her anymore. Perhaps one day she will seek contact with you. It may be healing for you, though I admit the risk of further disappointment as well. But I can say that regardles of your mother's poor choices, there is also healing in forgiving. Perhaps you already have, and perhaps you don't want to. This is of course your choice. But I at least wanted to mention it. I'm glad you have a good father and step-mother. :)
Truth is, my stepmother and me never liked each other until I moved out. Now we get along quite good.
And I think if my mother seeks contact again, I'll tell her that it is way too late for that. I really don't remember big parts of my childhood, but my father told me that while I was living with him, she often promised to get me for the weekend, but never showed up. She abandoned me three times and I won't give her a chance to disappoint me again. I have not forgiven her, but I don't really hate her. I just don't care anymore.