The slow descent

I had a story idea the other day that I wanted to catalogue somewhere because it's not something I'm going to use any time soon. It's actually more of a character idea than much in the way of story, but it has implications for story that could be interesting. Essentially the idea is watching a character slowly fall apart as he's trying to keep it together on some front. Not a particularly original thought there, but how it's done makes all the difference. My idea was this would make good novel material since film tends to reduce so much of the subtleties of character in it's condensation process. So much of the meat of the story would be the internal struggle against the continuing poor choices that it would be very difficult to get that on screen.
Initially I thought just the ever so instantaneously molecule of a moment that this would be a interesting to see someone's descent into pedophilia, but in the end I just couldn't even begin to think about writing that character. Still it gives you the idea of what I'm talking about, the slow descent through the poor momentary choices that lead us to making a horribly awful decision about something: murder, abuse, armed robbery, whatever. The point of the story would be watching this happen to the character, and watching him or possibly her struggle against there own seeming inevitability. That would be a key psychological trait, that they see this awful possibility looming in their future, and every little thing they do wrong leads them to believe that they are incapable of stopping the process by which they move towards this possibility. They struggle against it, but the slightest moment of distraction leads them closer.
This kind of thing interests me greatly. How someone gets to a place where they might consider killing someone or abusing a child or even simply (within the context of this sentence) cheating on their spouse or significant other. It's a gradual process whereby they move farther along the continum of destructive behavior until at some stage you reach a kind of sudden and momentous moment when you are faced with a really messed up possibility, and you are actually considering it. I think it would be really compelling, if well written, to look at this process in depth, and see someone go through it, especially someone who was themself self aware of the fact that this process was ongoing in their life. Whether or not they give into the temptation or not, I don't know. Maybe, and this I would love but would be horribly problematic in terms of actual publishing, it's unresolved; the book ends right at the moment when the decision is about to be made, and the readers have to decide for themselves based on the whole thing what the outcome is.