I can tell you haven't gotten far into Ashley's story haha. Those who hold your same opinion on the earlier parts of Ashley's story come to regret it later on when things start to make sense. Out of any main character in the game, Ashley has the hardest shell and it actually takes a while for you to understand her. I can't say she has problems worse than slavery, but she has some very rough problems as well. Just keep playing, and try to read between the lines. Maybe even watch her room's cameras ;)
I'm also not quite sure which extreme reactions you're talking about, but this is probably hyperbolic. She has also never pulled a knife on MC in a serious way. And has never raped MC. Ashley is a broken person with many problems that get resolved. All characters in HH grow a lot from the first time you meet them.