This was not your fault. Have you ever heard the phrase learned helplessness? If you're in a situation where you have no hope of it ending or changing, you learn to just accept it - as a means of survival. You did what you had to do to get through an awful situation that you should never have had to tolerate.

Sometimes knowing things logically isn't enough, because we second-guess ourselves and don't dare believe what we know. I'm really sorry this happened to you. It wasn't your fault. Abuse never is.