Mom and daughter issues

My mom and I definitely don't have the best relationship, but today took the cake. We were going over the rules for something she was forcing me to go to. I kept saying "Okay" to everything she said, and apparently she thought I was being rude by 'not listening' to what she said. Although, I was listening. She smacked me upside the head and yelled, "Why can't you ever be a good daughter and listen to me? Why did I even have you?" I wanted to cry. But I was out on public. I asked her why she hit e but she just hit me again and said, "It's just a little pop. Get fucking used to it." I feel awful.