Your AH's family could be my extended family. I had one particularly abusive cousin who would, on occasion, mess around with me for kicks. One time, when I was around 8 or 9, he told me he was going to kill me after physically forcing a kite out of my hands and hitting me and so I told him that I hated him.
They saw what had happened and my parents expected to apologize because he was "our guest". Although I was very young, I also realize that this was extremely screwed up thinking, so I made it clear that I did NOT want to issue out an apology. My father remembers this moment and it is one of his greatest regrets. (My cousin continued his violence into his adult years and should probably be institutionalized.)
I had to rely on books and TV to see what happy, functional families could look like, to remind myself that my extended family could hold itself to a higher standard.
Your daughter is so lucky because she has you.