Being bullied as a child leads you to learn patterns of behavior that will avoid standing out. You change who you are. If you do it long enough, it becomes an easy default, and you feel like you're someone else. You live a second life, one which is true, and one which is for public consumption - for people you aren't sure of, that you fear are waiting to betray you or bash you for being different. It's dissonant, even draining. All you can do is find support, start unraveling the protective facade, and see what plays out.
Step 1: getting to the point that you realize you need to do this.