My team consists of my boss, a senior coworker, 3rd coworker and I. My boss is the CEO of the hospital and should not be my boss because he has no idea with what we do. He allows my senior coworker to run the department, so we basically report to her. Although she's senior and has over 30 years of experience, we all have the same title. This senior coworker has caused 2 people to leave within 6 months (one left in 6 months and another in 2 months). Then I got hired and the 3rd coworker was shortly hired after me. The 3rd coworker and I have slightly over one year of experience. I hated my senior coworker for how she treated me, but I have realized that she wants power and is very insecure with herself. Although I only have 1 year of experience, I used to work with some of the nation's smartest people in my field. I guess my coworker felt very threatened with the ideas I bring in. She would shut my ideas down and make me do unimportant things that are not useful for my job. She wants my 3rd coworker and I to do everything her way, even with the way we write. We need our approval before we send out an email. She expects us to tell her whenever we are out of the office (our role requires us to go out a lot in the hospital). She requires us to tell her when we take lunch and even use the bathroom. She likes to “test” us by randomly asking us questions about healthcare. Then she would laugh at us when we dont know it and would require us to search it. Sometimes it's not related to our job. Other times it's some of the easiest questions in our field or it would be so broad. For example, she would ask, “Tell me about covid.” I would ask her the symptoms and she would correct me that I am wrong and she would mention of infectious period. She wants to correct us to boost her ego. The 3rd coworker (who I get along with) has been acting immature with my senior coworker by randomly asking her broad and stupid questions and saying mean things like “Omg, you don't know. You've been doing this for 30 years.” Honestly, I feel like one of these days, I might explode in front of her and ask her to stop asking me stupid questions. I realized that she treats us kindly whenever we do all the unecessary things she wants. However, in a way, she feels happy because she has power over us. How do I deal with her? I'm seriously considering apply for another job because my boss refuses to acknowledge that my senior coworker is the issue. They have their private meetings before and after work and often leave my 3rd coworker and I out. I know for fact that they tried to fire my 3rd coworker, but HR didn't allow that to happen because we had 2 turnover in a short period. Once I get a job, I will leave, but I want to be able to deal with her professionally while I am here before I ruin my mental health.