I have something similar. In fact, tonight I think I had a psychological breakthrough. I have been diagnosed with BDD. Anyway, I usually feel like you said, pretty OK, and then there's this other me, which thinks I'm hideous looking. I've finally realized that when I get depressed, I think I'm 100% hideous -- totally forgetting and not believing that it's really 50% okay and 50% ugly. I see myself in two ways.
Well, amazingly, today I realized that neither one is a delusion!! This is major!! They are BOTH true. It probably sounds silly to someone who doesn't have BDD (Body Dismorphic Disorder, see http://www.bddcentral.com
for more information), but we BDDers feel we're ugly and hideously deformed. The docs say it's a delusion. I felt it was simply the truth, not a delusion. But today, coming out of a deep depression, I realized that I really WAS having a delusion when I thought I was 100% hideous and got depressed. That's a delusion because I'm not 100% anything -- I'm 50% cute and 50% ugly, or 60%/40%, or another proportion.
So, analagously, you are not 100% pretty ok and then 100% thinking you may be crazy or going crazy. You are BOTH, in probably varying proportions over time. I fell into the snare of "black-or-white thinking" that said I had to be 100% of something. That's also called "all-or-nothing thinking." That's a delusion.
We are never 100% of anything -- we are a mixture! Maybe you're thinking you have to be 100% of whichever "you" comes "alive" at the moment? Is that possible, do you think?