WordNet (r) 3.0 (2006):

go to pieces
    v 1: lose one's emotional or mental composure; "She fell apart
         when her only child died" [syn: fall apart, go to
         pieces]

Moby Thesaurus II by Grady Ward, 1.0:

77 Moby Thesaurus words for "go to pieces":
   bite the dust, break, break up, canker, carry away, cave in,
   collapse, come apart, come off, come undone, come unstuck,
   conk out, corrupt, crack, crack up, crumble, crumble into dust,
   crumble to dust, decay, decline, decompose, disintegrate, droop,
   drop, fade, fail, faint, fall, fall into decay, fall off,
   fall to pieces, fester, fizzle out, flag, flip, fly apart,
   gangrene, get loose, give out, give way, go bad, go downhill,
   go haywire, go into hysterics, go soft, hit the skids, languish,
   lose courage, lose self-control, mildew, mold, molder, mortify,
   necrose, peel off, peg out, peter out, pine, poop out, putrefy,
   putresce, rankle, rot, sink, sphacelate, spoil, spring apart,
   start, suppurate, topple, tumble, unravel, weaken, wear away,
   wear thin, wilt, yield