Answer: sillyme

AnswerCrossword Clue
SILLYME

[Headslap]

SILLYME

"I should've known better"

SILLYME

"What a fool I am!"

SILLYME
Words before "And here I thought ..."
SILLYME
Verbal alternative to a head slap
SILLYME"Gosh, what was I thinking?!"
SILLYME"What was I thinking?"