Teaching psychology classes at Granite State College makes my ears always perk up when I even hear the word "psychology." (There's a similar effect that describes how we are likely to hear our own name, even when in a noisy crowd and no one else heard it. It's called "the cocktail party effect." Social psychology has a million of those cool ideas!)
So back to Tugend's book. She points out that the important difference for those with perfectionist tendencies between a psychologically healthy perfectionism and an unhealthy one is whether those tendencies "rule - or ruin - their lives." An example she gives is a person she describes who likes all the glasses in his cupboard lined up in a certain way. If anyone puts them in a different order, he doesn't freak out. And he doesn't expect to be perfect in everything he does.
I see tendencies like this in my adult students sometimes. Students in my adult online classes have to write papers, and when I carefully correct any errors, I sometimes get an anguished response that they "can't believe they made that mistake." I try to remind them that that's what being a student is. It involves learning, not being perfect to begin with!
So don't think of mistakes as "nasty secrets." Think of all the learning you can be doing if you don't demand perfection from the beginning. At Granite State College, we'll give you the best we have to offer and you may just end up feeling close to perfect!