Adult-Adult relationship w/boss

My boss is known (and professes) to like to fire people. In the back of my mind, I worry I will be fired someday, so I try to be the perfect employee, always one step ahead, but often feeling a combination of resent and powerlessness. She is reactive and often times unreasonable and, in my opinion, a poor childish leader, punitive and fear based. Ok, so now I have all of those terrible descriptions out, I need to learn how to manage my emotions when I interact with her. I feel like a scolded child when dealing with her and I retract into a place of scarcity, powerlessness and manipulation. HELP. My physical reaction when I deal with her is a surge of shame and anger. It is truly horrible.
C: Boss
T: Do not trust
F: Scared
A: manipulate, retract, react
R: Dislike myself

I really do not like my reaction to her. I feel like a powerless child running scared and trying to second guess her.
This is not the way I want to live my life.
Right now, I do not feel like I have an option, I feel lucky to have my job, and want to try and keep, but some days I want to say *uck it and quit. Live life on my own terms – I know I need to learn how to navigate these type of people and situations in my life from a place of power. I know that I am having this experience independent of her. It is a reoccurring theme for me (feeling helpless and scared); I attract these types of people in my life. I want to resolve this once and for all.