I'm not really sadistic at all, but I relate to the "being ill at ease with his base desires," part, which is probably why I kept going through the discomfort of the unsavory bits. And for some reason I feel like sharing, so it's storytime.
My sexuality was always too strong and felt like something external rather than part of me, and as a result it felt like something was reaching into my head and forcefully twisting my thoughts, usually in directions I didn't like. Like being violated by my own biological impulses, it made me feel dirty and hate myself. I had fantasies about cutting off my balls, and it wasn't some extreme masochistic shit but just wanting to be free of it. I developed a distaste for sexuality itself rather than just my own, which I never understood how much was because of that and how much is just based in the reality that the deepest darkness in humanity is almost always connected to sex. I think I managed to mostly explore and get over that, but how common creeps are still makes my stomach churn to think about.
I actually used to use indulging in porn and such as a means of punishing myself, using the feeling of degradation and self-loathing it brought about. I didn't really fix anything either. I eventually started taking a medication that had a side effect for me of greatly diminishing my libido, which was a tremendous relief for me. It weakened to the point where I felt like I was in control, not it. I guess because it was a pretty major struggle in my life, I developed a pretty strong interest in stories that explore sexuality as a theme without pussyfooting around the specifics. I am not the same as the MC, but I can't help but relate to a sexual internal darkness that you develop a morbid fascination with and have trouble looking away from even if you don't like it.