Distancing yourself from negative family members.

I will start off by saying that my sister and I used to get along great. We used to be best friends. We were only 3 years apart. She then got a job at 16 and she met her current boyfriend. They've been together for 7 years now. Well, since she's been with him the entire family has noticed that she is rude. She thinks so highly of herself because of her boyfriend. She always speaks her opinion even when it's unwanted. She crosses the line so many times it's unreal. Well today I was venting to her about something my Fiancée and I are going through and she totally snapped and just said something that was unnecessary. She said I didn't help plan my own mothers funeral or go through her belongings. Which at the time of her death I was only 19 and they didn't include me on a lot of important things because they thought I was young and not mature enough to handle the truth. So today she takes a stab telling me that, knowing that my mothers death was traumatic to me. I honestly didn't even reply back to her. I deleted the text as soon as I read it and now I'm seriously considering distancing myself from her. I will also be moving out of state soon and I'd rather ignore her until I move. She really broke my heart by saying that. This isn't the first time either. When I got engaged a couple months back, she was jealous because her bf still hasn't proposed and she's been with him longer and she's older than me. She thinks she "deserves" it more than me. She even said that I didn't go to a real college. She is mad because I can make more than her and go to college for 1 year shorter than she had to. She's always resented me for having an "easier" life saying she had to go through harder things and I'm spoiled. Would I be wrong to just quit talking to her? I mean she always offends me with every chance she gets. She even makes fun of me for having a smaller butt and smaller breasts than her. I always cry behind her back. I never let her know how upset she gets me. Bc I always tell myself she doesn't mean it. I don't understand what she has against me. Give me advice please ladies.