crumble

(verb) fall apart. Synonyms: crumple, tumble, break down, collapse. Examples: "The building crumbled after the explosion." "Negotiations broke down."

(verb) break or fall apart into fragments. Synonyms: fall apart. Examples: "The cookies crumbled." "The sphinx is crumbling."

(verb) fall into decay or ruin. Synonyms: decay, dilapidate. Example: "The unoccupied house started to decay."