Will you please help me?

I don't know what to do. My sister is always being mean to me. All she does is insult me. She never gives it a break. I try to be nice to her. I can't even be mean because I am too nice of a person. I am just tired of people insulting me and being mean to me. I tried to tell her how she makes me feel but the only thing she said was "Want me to punch you? You better shut up!" Like, this morning we were discussing about how I would get to work. And, my dad had said maybe my sister could drive me. My sister said "She can walk there." My dad said "It takes 15 minutes just to get there by car...it would take about an hour to walk there." I said "So, will you drive me there?" She said "Well, I guess you can just walk there or lose your job." See, my dad couldn't take me there because he was already at work and we were in the house on the phone talking to him since my sister and I were still arguing about how I would get to work. So, what do I do? The problem is that I am in misery about just everyday. I am hardly ever happy. Plus, I am always worrying. My parent’s try their best, but they aren’t all that supportive…or so that it seems to me. So, what is your advice? I don’t have that many friends by the way…in person that is. I have several internet friends…