AITA For Calling My Coworker Abhorrently Unprofessional?

I (18F) work in a laboratory preschool at my high school, which is where several students who are taking a class work in a preschool as basically an internship. One preschooler in particular, a little girl I’ll refer to as Shelby (not her real name for privacy), is assigned to me as my key child. a key child is a student that a teacher is assigned to be with and monitor their development. Shelby is the sweetest little thing but is a very anxious child. She lost her mother when she was around a year old and is always worried about people dying. She’s severely attached to me and has been from the very beginning, and that’s part of the reason why she was assigned to me. One of my coworkers, Vivian (18F), is very much in this for herself and not the kids (constantly wanting things that are meant for the kids, gets upset when she can’t have food from the snack cabinet, writes lesson plans based on what’s fun for her and not based off educational value, etc). She is always very snippy about me having a key child and not her. She keeps getting irritated when Shelby wants me, gets angry when Shelby brings gifts for me but not the other teachers, gets annoyed when I’m carrying Shelby, etc. Today, Shelby was particularly clingy (her dad said she had a rough night last night). For the entire day, she was either being held by me or sitting in my lap. During Vivian’s lesson where the kids were helping make slime (which she does for nearly every lesson), she asked Shelby to pour the glitter in and Shelby said she didn’t want to. Vivian made a snarky remark about how if I wasn’t assigned to her, Shelby wouldn’t be having rough days so often. Shelby & the other students didn’t really seem to notice the remark, but it pissed me off. After the students went home for the day, I pulled Vivian aside and told she was abhorrently unprofessional and needed to fix her mindset before she caused detriment to the preschoolers. She called me a bitch and said there’s no reason for me to be with Shelby so much and that I need to let her be more independent and let her get close to the other teachers. I still think Vivian was unprofessional, but I feel like confronting her may have been rude. AITA?