Childhood PTSD afraid of authority

Hello, I am new to the forum and I am looking for help to better myself. When i was 6 my mother passed away from cancer and 7 months later my father got remarried and she turned out to be very abusive mentally and physically. I lived with this for 10 years when I came home from school and all my stuff was on the curb, I was 16, so I left. Every day she would tell my little brother an I how worthless we were and how we didn't deserve to be alive, the world would be better without us she would say. We weren't allowed to do anything except sit and read, no friends, no tv, no talking to each other, only allowed to use the bathroom 2 times a day, etc. She was so controlling and every aspect of our lives was controlled by her.

After awhile I developed this feeling, for instance the best time was when she had to work because my father didn't enforce her rules, but when she was supposed to work and she would get called off for work, my stomach would drop and I would feel sick and hopeless. After that feeling happened 100's of times, now years later every time someone with authority is around me I get that same feeling. I get pulled over by the police and i get that feeling, then they think something is wrong because i look sick all of the sudden. When I have to meet new people of authority I get this feeling too.

I'm not sure how to control the feeling or what it even is but, it is somewhat crippling my life and leaving me with little confidence. Then I get depressed and so on. I also worry until I'm sick. I should be able to walk into a courthouse to get papers without feeling like this. Thanks in advance.