Coworker treating me especially terrible, and I don't think HR will help
I work at a semi-small family-owned pizza shop that employs probably 100 people across all three locations and our bakery. I've worked for the company for around 2 years, and I really love my job and almost all of my coworkers. I have been considered for a promotion a few times, but because my availability is limited, I've been passed over for someone with a more flexible schedule.
The coworker, whom I'll call Anne, was hired about six months after me. I was already working my way to a promotion by then, and while I was really shy, I knew I was really a part of the team and well-liked by everybody (still mostly true).
Anne and I really hit it off in the beginning, as we had a lot of things in common and our personalities just generally worked as a duo. She was pretty good at the job from the beginning, and after she was trained, I felt a lot like we were equals (I worked only 3 days a week whereas she's full time, so my skills/experience built much slower).
However, after a few months, she suddenly started avoiding me, acting short with me, and nitpicking everything I did and going to one of our managers (whom everybody dislikes) about every breath I took. She developed a sort of nose-in-the-air attitude, like she was better than everybody, but she seemed to treat me especially different. I started getting really anxious and stressed out when I was on shift with her, always wondering what she was going to get me in trouble for next, which led me to make more mistakes than on shifts without her. I had to go home sick a couple of times because the stress was affecting me so much.
Back in October-November, I got an announcement on our schedule app that she was going to be a supervisor. And I >!threw up everything I ate.!< I had one of the worst panic attacks of my life, and nearly quit my job on the spot.
She makes me feel like I'm totally beneath her, and like I'm a horrible person just for existing in the same space as her. I have no idea what I did to deserve this kind of treatment, especially considering we went from getting along really well to not getting along at all.
She recently did something (I won't go into specific detail, but it just highlighted how terrible of a person she is) and the entire staff has beef with her. And many of them have come to me to say they see what I was trying to say all along. She's been making nice with all of our other coworkers because almost everyone stopped engaging in her drama, but not me.
She talks bad about everybody behind their backs, even going as far as to actually insult them to other people. I mostly ignore her when she's around, but because she's my direct superior, I have to listen to her enough to not get myself into trouble. I think she knows this because she'll delegate every task she can to me while basically standing around talking with my other coworkers. The only times she's helped me while I was drowning on my station was when it could make her look better and me look incompetent. Apparently, she's been talking especially bad about me, but I don't know the extent of what she's saying (I do plan to ask around and find out, however, so I can decide if I should be concerned or not)
I've asked her directly several times if there's something I did that's upsetting her, and the answer is always the same: it's not me, she just has something going on and it's affecting her emotionally. Every. Single. Time. I'm really starting to feel like her punching bag
I don't know if this is something I *can* bring to HR. I trust the coworkers that came to tell me what she's doing and that they see the way I'm being treated, but our HR lady has brushed me off a few times in the past, so I'm hesitant to bring something like this to her. I can talk to our GM, and he'll at least have some good advice on what I should do, but I don't want to bother him with something like this because he's very anti-drama. I've also been really afraid she'll retaliate in some kind of way and make things even harder for me or try to push me into quitting.
Should I ask the coworkers that came to talk to me to help me talk to HR and/or the GM, or try to handle it on my own? Is it even with trying to handle with the upper management? I don't want to sound bitter/spiteful because she was chosen over me for the promotion like I think they suspect, but I don't want the continued tension either. And is there any way to word it so it comes off as professional rather than just complaining?
Tl:dr my coworker, Anne, has been treating me like I'm completely beneath her, talking tons of shit about me behind my back, and giving me extreme anxiety and panic attacks just from being on the same shift. I don't have the confidence HR will handle it because I've been brushed off in the past, but I really feel like it needs to be addressed. I've tried addressing it directly with Anne, and she's said there's no problem but continues to treat me terribly.