I personally haven't struggled with this in regards to my work, but:
I feel this. Hard. I've worried about being a bad person and no reassurance of the contrary I get from others is convincing. Again, my hangups weren't actually art related, but I relate to being trapped in this particular spiral.
Don't take what I'm about to say as absolute advice I'm telling to follow, as I'm well aware it's not stuff that you can just wake up one day and do. And it might not work out for everyone. Just ... here's what's helped me:
Stopping myself from seeking assurance
In my case, I guess I was 'lucky' in that I felt unsafe seeking reassurance about my particular hangups, so it was 'easy' to stop myself, in a way. But not many people are going to shit on a creator who's insecure about their work, particularly if they're creators themselves. And that's great! But it does make it incredibly difficult to resist seeking reassurance, when there's no equal and opposite force to push back against that urge.
The fact that you find the reassurance unconvincing^ might actually be a good thing, as harsh as it is to say. I also found it helped to ask myself: if I got the reassurance I'm craving right now, would it actually make me feel better? If the answer is 'no', it makes it easier to stop myself. But if you get genuine relief from that reassurance, it's easier to stay hooked on it, if it that makes sense. This is not to say that it's true that people are only complimenting you be nice - just that if you feel that way ... you can leverage this.
What got me though this is convincing myself that even if my fears were actually true and I AM a terrible person, it's not the end of the world. Looking practically at the implications of this worst case scenario, nothing bad actually happens. No-one gets hurt. It's okay.
So in your case, think about what would happen if you ARE actually a bad person, made a bad work and butchered all your precious ideas? Who gets hurt? What gets destroyed? Can it be repaired? Let your mind run free and don't shy away from uncomfortable possibilities, otherwise you'll probably not feel very convinced if you do conclude that actually, it's probably going to be okay. But take your time. Don't feel like you have to do this all at once.
Also, not trying to diagnose an internet stranger here, but I recommend looking online and reading about people's experiences with OCD (e.g. on r/ocd). I'm not sure I had OCD myself, but I found a lot of it quite relatable and helpful
^ I get the feeling this is kind of like building up a tolerance to a drug, and you'll need higher and higher doses to satisfy the craving. Which would usually be bad, but fortunately you can't overdose on reassurance