We all have lapses in common sense, self-judgement, confidence... it's what makes us human, and that's mentally disordered or otherwise! It's what we do in these lapses that harms us, though. Ride through the lapse and you're surprised at how trivial it seemed in hindsight.
Ever stood in line for a roller coaster and started to panic, freak out, lose your mettle, stop, try to get out of the queue, but you're through the barrier, flip out, now everyone around you is thinking you're a total drama queen, and now it's too late... you need to board, you're freaking out more, OH GOD, THERE IS NOTHING THAT WILL TOP THIS, I AM GOING TO DIE.
And then when you've gotten off the other side you realise, "wow, was I freaking out over .. a ride?!" And you laugh about it with your friends afterwards? About how this safe, normal, utterly trivial thing suddenly became life or death whilst everyone around you just... got on and had fun?
This is the life of an Eating Disorder sufferer. AM I FAT? OH GOD, I'M FAT. I AM 3LBS MORE. I CAN'T TAKE IT, THIS IS TOO MUCH, I THINK I ATE ONE MORE MALTESER THAN I SHOULD HAVE, OH JESUS. But it's part of the disorder. It's the trivial, simple, mundane things that others shrug off and say, "oh well then, better mental-note that and move on."
Don't be ashamed; simply understand that it's your neuroses running rampant, and this is one of those lapses of judgement. This is you in the queue for a rollercoaster.