Pretty much what everyone else said. And you know, I know people "tend" to become abusers when they were abused as children and all that . . . but it's just that, a tendency, just like people "tend" to become lickspittle collaborators and sell people out when they're living in a dictatorship. Lots of people do not react to bad situations by passing on the bad in turn. Take for instance our heroine. And for that matter, lots of people act like jerks because they're spoiled, not because they were traumatized--or, just because they're jerks.
And I find this kind of canned. Just not really buying it; even though I was half expecting it, the story doesn't foreshadow it at all, and while there are some kinds of bad behaviour that tend to stem from abuse, I don't know that her style of action is really one of them. This is the problem when stories are told by people who are too nice--they can't bear to have anyone simply have a bad personality, simply be in the wrong. But while one-dimensional villains are kind of unrealistic (except Mohammed bin Salman maybe), nobody ever being a creep except as a result of trauma is even more unrealistic.