i hate my coworker and i am not sorry

sooo like last week at work things just got cray cray. i have this one co-worker let's call her sarah, she is a total know-it-all but honestly i feel out of the loop with her sometimes, like she knows way more than me about how stuff works here and it feels like she thinks less of me for not knowing. anyways, so last week we got a new project and it was supposed to be collaborative, but sarah basically took over and started dictating everything to everyone else. i felt totally ignored, my ideas were sidelined completely and i swear every time i opened my mouth to say something she had already said what i wanted to say but better and then dismissed me as just repeating her. it was so annoying and frustrating. anyways i finally snapped last friday and when she started another tirade about the project being her baby i told her straight up that if she thought this was all about her, she was sadly mistaken. there are other people on this team too and i am not going to let her treat me like a minion. everyone else seemed kind of shocked but also impressed that someone finally stood up to sarah. honestly if anyone thinks it's wrong for me to be done with her after this they can just shove it. am i the asshole here?