I totally get you OP. I joined a new company a few years ago which I loved but I after a couple of years of being absolutely gas lit the crap out of by somebody. There were so many horrid little behaviours, but each one individually seemed far too small to raise, and like you, I know if I did they would be easily dismissed as this person" just being helpful" or "just ensuring everything is ticking along".
One of the many things they did was to sometimes send really overly formal emails to me about incredibly minor things, and worst of all, it would often after my initial training period be things that they had misinterpreted, overlooked, or anticipated that I wouldn't have done when I actually had. So they made me look really bad, and I would often read them with such acute frustration, but decided the best way to tackle this behaviour was to just ignore them completely and grey rock them, so I stopped responding to those particular emails.
One day they made the mistake of sending one of these emails from the shared mailbox instead of from their personal account. It turns out they were blind copying in a whole chain of managers trying to make me look bad, and I realised that they had almost certainly been doing this every single time.
I can't believe how underhanded they turned out to be and I found confronting the issue and raising it to be the only solution. I'm very lucky though that I got a new better role, but honestly I'm just writing this because I understand exactly what position you are in. I can assure you that this behaviour is noticed and looked down upon, and as long as you can point it out in a calm and professional manner, I would raise this with your line manager.
I doesn't actually matter her excuses about how she was "just helping" etc, the point is how her conduct made you feel. I'm also like you and can get really upset and teary at any conflict or particularly when I feel that things are unfair, so I benefitted from putting my thoughts in writing. I hope you do get it sorted, it's horrible working for people who think the way to get ahead is to put others down rather than shine in their own right.