I think keeping firm boundaries like you have (no netflix until chores) is sensible, as long as you are doing the same with your son.

I really agree with scorpiosis, I saw something similar happen to my older sister (I was the favoured younger one because I was more 'placid'), I would really try to get inside her skin and see things from her perspective. It sounds like she is feeling a lot of negative emotions about her place in the family, I would reassure her of her special place in your hearts and nurture every tiny positive progress made.

You wrote you are recovering from anxiety and depression, she may also be reacting against that, I know my son did when I was like that - it was years before he opened up and talked about it.