go to pieces
US /ɡoʊ tə ˈpiːsɪz/
UK /ɡoʊ tə ˈpiːsɪz/

1.
desmoronar, cair aos pedaços
to become so upset or nervous that you cannot function normally
:
•
After the accident, she completely went to pieces.
Depois do acidente, ela desmoronou completamente.
•
He tends to go to pieces under pressure.
Ele tende a desmoronar sob pressão.