Was this justified behaviour?

My mom and I got in an argument, and I thought it was over so I went back to to computer (my personal laptop is broken so I have to do my work in the living room). But my mom followed me and continued the argument even though we both knew we wouldn't reconcile our differences of opinion. She kept telling me to go to my room. At this point, I was really emotional. I have a history of letting my emotions govern my actions but I believe that we should act upon reason and facts instead of emotions. emotional decisions almost never result to be in our favor. most emotional decisions I've made in my life I can now count as "regrets." I am a cutter, I don't know if my parents know, since I'm smart and do my hips. But it isn't something I'm proud of, and I usually regret it later. this tells me that it is just an emotional decision that has no hold in logic. Would a clear mind tell me to cut myself open? no. would my emotions? Yes. Anyway she told me to go to my room but I wouldn't budge. I knew that if I went there, where my xacto is, I wouldn't be able to stop myself. She kept hitting me, slapping me across the face. I told her that her parenting methods were very inconsistent and asked her what good sending me to my room would be. All I could get in response was blubberings of "I'm the parent I say so" and i told her that unless she could prove that sending me to my room was going to magically fix the situation (it never has, come onnn) I wasn't going. After hitting me in the mouth a few times (classy, but this isn't about physical abuse. I'm used to it and I've already consoled myself that the people hitting me aren't my parents, they are the emotional urges that they sadly haven't ever learned to control) She kept calling my a psycho because i wasn't reacting to her. i sat there and said that she could be as violent as she wanted to me towards me, but it would only prove her wild and inconsistent parenting method and I would not be persuaded by force to go. Then she pretty much gave up and left, and now here I am. I'm a little emotional right now, of course, since after such a heightened confrontation and also the disappointment that a parent would hit their child so hard and so many times, and also i guess maybe a little distracted from the throbbing. (please don't comment on that) this post is not about her hitting me, this is about whether or not I was justified in not going to my room, to try to keep myself from cutting and also because I really don't have respect for wild, emotional, inconsistent parenting.