WordNet sense 1 (a sudden large decline of business or the prices of stocks (especially one that causes additional failures)):

crash

WordNet sense 2 (fall apart):

crumble, crumple, tumble, break down

WordNet sense 3 (cause to burst):

burst

WordNet sense 4 (break down, literally or metaphorically):

break, founder, give, cave in, fall in, give way

WordNet sense 5 (suffer a nervous breakdown):

crack, break up, crack up, crock up

WordNet sense 6 (the act of throwing yourself down):

flop