a home truth
An uncomfortable or unpleasant fact, especially one that is hard to hear or acknowledge. Often used in the plural. After growing tired of Paul's constant complaining, Jana decided to tell him a few home truths about his bad attitude.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
a ˌhome ˈtruthan honest criticism of a person said directly to them: It’s time someone told you a few home truths, my boy!
Farlex Partner Idioms Dictionary © Farlex 2017