This is some thread.
I'm personally fond of the Jekyll and Hyde analogy, and have written about it here on several occasions.
Turns out Dr. Jekyll's experiment was based on a resentment. He felt slighted, believing that he did not get sufficient recognition for all his good work, and he envied those who enjoyed a higher station in life, many of whom he believed did so without merit. He was also sexually and aggressively repressed, given the strict morality of his time.
By the end of the process, there was very little left of Dr. Jekyll except for an empty shell of the man. (Sound familiar?) I also agree with haennie, that it's a cautionary tail to wrongly attribute blame and/or responsibility to an "other" self that's disconnected from one's personality. When I acted like a dick when I was drinking, that's who I was when I was drinking. Virtually all of us experience guilt, shame and remorse for a reason. And that's not necessarily a bad thing.
In my experience, the road to long-term sobriety includes treating and caring for the whole person, no matter what the circumstances that contributed to occasions of bad behavior.
Note: Robert Louis Stevenson, the author of The Strange Case of Dr. Jekyll and Mr. Hyde, was experimenting with cocaine prior to writing his novella.