AITA for cancelling my sister's wedding?

My sister(F26) got engaged to her bf(M30) back in February. When my sister was telling me the news, I (F21) really didn't react much. This might come as a shock to many but I have never really liked my sister. We didn't grow up together, our parents divorced when we were kids, and my sister always took advantage of my shyness to bully me. I tried to forgive her and be more understanding in college, but she still used to bully me every chance she got. She even convinced a few of our mutual friends to bully me too.<br><br>For example, our mutual friend Sarah(F24) was one of my best friends, until my sister convinced her I was trying to steal her boyfriend. Even though I never showed Sarah any romantic interest, my sister managed to turn Sarah against me, and our friendship is now pretty much over. <br><br>I won't name all the other friends she manipulated like that, but she managed to turn most of our friends against me, and I'm pretty sure she was behind most of it.<br><br>When my sister got engaged, I didn't really react, and when some of our friends questioned why I wasn't excited, I just told them I had better things to do than plan my sister's wedding. Up to this point, my sister didn't say anything, but I could tell Sarah and a few others were giving me dirty looks. I know my sister convinced Sarah to dump her boyfriend, and Sarah has a child with him, but she still chose our wedding over her child's future.<br><br>When we got to discussing wedding details, my sister made it clear she wanted nothing from me except for my presence. She didn't want me to pay for anything and didn't want us to speak before the wedding. I told her I wasn't going to the wedding, and I didn't accept my sister trying to bully me anymore. She started screaming at me when I told her this, and when our friends stepped in, I just told them they had good reason to hate me. <br><br>My parents are mad at me for this, but honestly, my sister isn't the only one I'm avoiding. Sarah keeps trying to get me to talk, but I've told her I don't want to hear anything she has to say. <br><br>AITA?