I think there is no “M.E. Thomas” and the real author just created a composite character.
A true sociopath would never admit to being a sociopath.
Mental issues aren’t binary. There are surely a few genuine sociopaths who would gladly explain their nature to you in great detail - quite possibly because it positions themselves over you, a sort of benevolent threat & manipulation in lieu of opportunity to actually harm you.
I’ve dealt with clear narcissists; while they’re adamant about proving their superiority, and are quick to use mental harm for manipulation & self-affirmation, they’d not actually _hurt_ you. The author clearly had a history of physically harming others and lacking empathy, but learned to stifle it lest society harm (incarcerate) her in response; wouldn’t surprise me if she had neglected to mention a body somewhere with her DNA on it.
This sounds like a person who loves to talk about herself.