I am a perfectionist who hates making mistakes.  I am also human, and make plenty of them--mostly small, but sometimes large.  The way I  handle it is to try to admit errors up front, right away, to myself as well as to those around me.  That seems to defuse the situation for me.  I still get mad at myself, but at least I know I don't come off as thinking I'm always right.  And, if I can learn to avoid that mistake again, I'm one step closer to perfect, right?  LOL!

My biggest mistake recently:  I was running copies of a new report form that we'll be using this year.  It was designed in-house (but not by me).  Three of us looked it over before I started the copies.  After running a ream of EXPENSIVE paper through the machine, I picked up a copy and noticed there was a capitalization error--a GLARING capitalization error--that I (and the others) had somehow missed.  I was so upset with myself, and I handled it by subtracting a couple of overtime hours from my time sheet.  I didn't have to, but doing that helped me to sleep that night.