Wow, that's a tough one. I had sadistic tendencies toward myself and enjoyed bearing myself up emotionally. That's one way to stop it going "outward" and being blamed for it but I started it way back when I was a kid. Can't say it was rational, just what I did.

Since you're not proud of this, just find it gratifying, could it be a result of people treating you like that when you were a kid and not having a chance to do anything be about that situation then? If so, you might find therapy helpful, but I kind of hate to recommend that. I ended up in therapy for years that didn't help much and made things worse before I finally got to the bottom of things. I don't feel gratification from beating myself up anymore, though ,thank thankess, and don't do it much anymore. But it took like forever.