This struck me in your post:
He was always open about his feelings of abandonment and lonliness. His sadness that his father refused to remove him from that situation yet he's still very devoted to the man. His anger at being used and "taken" by others who felt they had the right to abuse him verbally because he was "different" because he'd been burned during the abuse. His long time anger, that we finally over came, regarding therapy and his feelings that it was all useless because it didn't provide anything to really stop his pain. All of the different parts that made up his suffering were never hid from his family, his friends or myself.
I don't know if it's normal, but I think it puts your fiance ahead of the game that he can recognize and articulate his feelings this well. It's much easier to be open about your suffering if you have a language for it. I don't think many kids are allowed to explore and verbalize their "negative" feelings-- I know plenty of very smart people, including survivors, who couldn't describe the difference between feeling lonely and feeling abandoned-- obviously they know the difference between the two words, but not how to distinguish between the two feelings.
Rustam makes a good point. A survivor's whole environment influences his decision to tell or not to tell. As a child he may think that no one who will believe him or respect how he feels about what has happened.
If your feelings are minimized constantly, if your trust is betrayed in little ways, if you have already been labelled a problem, why would you choose to share a painful secret? How many times do adults say to kids "That's nothing to cry about," or "Of course you like ____," or retell their children's secrets over the phone to friends, or cut them off in the middle of their stories? When you think about all the ways that even well-meaning adults can damage children's trust in them, it's not surprising that so many kids don't tell.