Unending Drama stemming from 1 incident

I’m using a throwaway account for privacy.

I’ve been working in a high-volume medical clinic for almost a year with coworkers who are almost all women. This dynamic is not new for me, as I have been in the medical field for 15 years, and most of my jobs have had staff composed of mostly women.

About 2-3 months ago, I was involved in an incident with an offensive coworker who had been calling me “Lazy Bones” for months. This day, she approached me “jokingly” talking down on me but with more snideness, so I told her bluntly to get out of my face and go work for once. Well, that hurt her feelings and she went to everyone in the clinic that day to tell them what I had said to her. I almost texted our manager to tell her about the situation, but I realized that it wasn’t really remarkable.
The manager called a meeting with me the following day, and the coworker falsely claimed that I called her a bad name in the midst of the conversation.

Since that incident, everything has been different. Initially, the offending coworker and her friends group were making it very uncomfortable for me to come to work — seeking me out to make sly comments about me and make faces and any other mean-girl/middle-school behaviors you can think of. HR “handled” that, threatening to fire the offender, but her best friend threatened to quit if they got rid of the offender, so HR has reneged. but now, I am getting the silent treatment from almost every other peer-level coworker OR overly nice treatment from few others. One of my best work friends who used to come to me to talk about everything is now given me the cold shoulder after spending one day working with the offending coworker. They’ve hired 5 new girls, and the offending coworker and her friends have told them about all the drama. One of the new girls has been very cold and rude with me since working with the offending coworker and her friends a few days ago, during which shift they did a lot of whispering and such. She treats me normally when no one else is around, though.

I’m just at my wit’s end. I have never worked at a job where I was actively/obviously disliked by so many people. I may have experienced this for a brief period during elementary/high school years, sure, but in my adult life, this is novel.

How do I overcome this? How do I tolerate such an uncomfortable work environment? I enjoy(ed) my job and wanted to grow here, but I’m just not comfortable anymore. My initial plan was to wait it out because this offender and her biggest ally break a lot of rules and get lots of patient complaints, so I thought it was only a matter of time, but her ally has been here 2 years so it’s unlikely that they’re going anywhere. I also thought maybe it’d just get better, but it’s not much better after 2-3 months. Advice?