1
general::
Experience an emotional or mental breakdown, as in When she heard of his death she went to pieces. [Late 1800s] For a synonym, see FALL APART, def. 2.
American Heritage Idioms
2
general::
Phrase(s): go to pieces
1. Lit. [for something] to fall apart into many pieces. • The vase—which had been repaired many times—just went to pieces when I put it down. • When the window was hit by the ball, it went to pieces. 2. Fig. [for something] to become nonfunctional. • His plan went to pieces. • All her hopes and ideas went to pieces in that one meeting. 3. Fig. [for someone] to have a mental collapse. • Poor Jane went to pieces after her divorce. • Fred went to pieces during the trial.
McGrawhill's American Idioms And Phrasal Verbs