A figment of your imagination. Not her existence, by any means, but the idea that you have of her. The idea that she's this perfect, kind, beautiful, loving and respectful being, whom you should dedicate your life and heart into. The future mother of your kids, whatever. It's all an illusion and it's all in your own head.
In reality, she's the girl who lets that asshole disrespect her and loves it. She's the girl who uses guys for her own ends. She's the girl who leads men on without any care just because she can get more attention and favours from it. Do yourself one: Stop fantasizing. Move on.