Well is not really about justifying abuse with the excuse of "I was abused in the past".
We have to put ourselves in her shoes at least a bit. She was raped/bullied by her father and friends, and she became "stronger", killing her "weak" self, which gave her a twisted and fucked up sense of "to become stronger, you first have to suffer" or "no pain no gain".
Is it logical? no, but that is the idea. Because of her experience she became mentally unstable, and she forcefully pushed her ideals into Eyama to try and get him become "stronger", which in turn made him probably even more unstable than her.