set the record straight
US /sɛt ðə ˈrɛkərd streɪt/
UK /sɛt ðə ˈrɛkərd streɪt/

1.
to correct a misunderstanding or a false impression
:
•
I need to set the record straight about what happened at the meeting.
•
Let me set the record straight: I never said that.