It sounds like a survival technique. You were in an abusive situation so you're body was used to always being on guard. Unfortunately those survival behaviors get ingrained because of the stressful situation and are hard to break. The brain sucks sometimes doesn't it?

Stay strong,
Jessica

You are in this snowglobe. It is encovered in glass and secure. But one day someone comes and shakes the globe and the pieces go flying everywhere. Now they will eventually settle but they won't be the way they were before and they can never be that way again.