Idiom Definition:
"to set someone straight"
to inform someone about the actual facts of a situation when that someone does not have the actual facts or is ill-informed
Synonyms:
acquaint, advise, apprise, brief, edify, educate, enlighten, familiarize, forewarn, illuminate, instruct, invest, level, notify, relate, show, teach, tell, tip, update, warn, wise
Literally,
setting her straight. - - - - ->