Interesting perspectives. You kind of describe my XAH, only he was also an alcoholic. But at the end, after 5 years, I realize I didn't really know him either. He never let anyone that close. I used to refer to him as having this wall with gates made of metal that clanged shut when someone tried.
Now, that said, I too am an emotionally closed person. I have few close friends and family who I share my "true self" with. And it isn't about trust issues or childhood traumas. I am simply an introvert. I just like it that way. I had a therapist tell me I was emotionally unavailable once. But I just don't think its that simple of a diagnosis.
So how are you supposed to "work on" sharing your true self with others? Did the therapist give you some tips/homework?