I dont think you can just “let go and move on.” If that worked, who would need therapy?? I think it’s important that you allow yourself to grieve for that girl and woman who was mentally ill and didnt get the help she needed and suffered terribly. Write about it, talk about it, make art about it. Let yourself feel the deep sadness and anger and mourn. After that, it also might be helpful to take a deep dive into answering the question you ask: who might she have been? What might she have done? And then use the answers to those questions to face forward into the future. What would living your best life look like? Because the best revenge for past trauma is a life well lived today.