Is it child abuse that my father physically beats me?

My father has always physically beat me, but he usually does it as a form of punishment. He claims that it's all right and I kinda believe him, but I'm starting to be afraid of my own parents because he does it so frequently. He punched me hard in the stomach when I mentioned not enjoying clarinet anymore and threatened to break my clarinet. Even if this is child abuse, I don't really want to tell anybody about it for fear that I would be left without much of a family and my family would all hate me. He's also not entirely bad but when he's pissed off he'll usually physically beat me at the sound of the words shut up. My mother and brother also tend to take after my father. I think my brother might have broken (or seriously injured) my back when he was beating me one time because ever since that day I have had the worst back pains and I am the only child my age with back pains. As far as I'm comcerned usually only older people get back pains. I always hear about my father having back pains. My father has also scared me before by joking around and trying to feed my dog, whom I love dearly as she is the only real family I have, beer. For those of you that don't know, dogs can die if they drink beer. Luckily I stopped him before she drank anything so she is still alive. Am I wrong or is my father actually an animal and child abuser?