The idea that someone loves you just because they are blood related to you is sadly false. Not everyone is meant for parenthood: not all mothers love their children; not all fathers love their children. But whether they love you or not is not really relevant. It's not okay for someone to abuse you no matter how that person feels about you. Sometimes there are reasons that a person turns out to be abusive, and it's good to understand those reasons, but it still doesn't make the abuse okay.
I would be mad too.