She is a survivor she got through that part of her life, so she can get through anything. The last part of the song goes like this
There's a part of me I can't get back/A little girl grew up too fast/All it took was once, I'll never be the same/Now I'm taking back my life today/Nothing left that you can say/Cause you are never gonna take the blame anyway
To me this means that what happened when she was a little girl forever changed who she was, but she is not going to let what happened run her life anymore, and that the person that caused her the pain would never admit it. The feeling of the song changes from sad to angry to a sort of empowered feeling. The reason I love this song so much is it made me feel like I was not so alone in what I was going through, and that there would be a point in time that I would be able stand up and say this is enough I don’t have to feel this way anymore. That this situation I was in only made me a stronger person. It may have made me grow up a lot faster than most kids, but if it had not happened I would not be the strong person I have