Don't feel bad for leaving, your health is more important than anything. I did the same. In the contrary of you, I had a mob against me. It started with 2 women who were jealous and would side eyed me, and bullied me. I ignored them and tried to do my job and they spoke on my back and turned their colleagues against me. One even assaulted me. I left because the HR didn't do anything to the woman who assaulted me, they even tried to put it on me.... Like you I suffered anxiety and flashbacks and anger because I didn't get justice. I know that I won't let it happen again and I try to be selective of where I work and to assert myself. There are a lot of toxic, narcissistic and unhappy people out there. I think the best you could have done was to ask to change team or confront her openly and strongly. I don't believe in being friendwith these types of people.