Incredible story, thank you for sharing. About your last part, I would tread lightly with your DM person. Of she hasn't had proper training, especially with the boyfriend prooving to be violent, the best thing for her would be to get out and go to a friend or fanily member that will not let her go back. If she were to engage him with violence, he will likely respond back with more force than she is expecting (similar to how you respond back to the boys who underestimated you). Of course she should defend herself, but in cases of domestic violence, returned violence isn't usually a safe answer for the victims.
RE: Self-defence Lesson From My Father