let (one's) emotions show
To allow one's emotions to be on display to others; to let other people see how one is feeling (about something). He is normally a very composed, reserved fellow, but he'll let his emotions show if ever you say a disparaging remark about his sister. She held it together for the whole funeral, but she they started talking about her childhood with her father, she started to let her emotions show.
Farlex Dictionary of Idioms. © 2024 Farlex, Inc, all rights reserved.