Need a word for "Unravel in the worst possible way" [closed]

I like the word disintegrate for your sentence. (Although I don't know that it's any less "negative" than crumble.)

Wordnick offers these definitions:

To become reduced to components, fragments, or particles

To undo the integrity of, break into parts

To separate into component parts; reduce to fragments; break up or destroy the cohesion of

(Note: Be careful about a run-on sentence.)

You could follow Yeats and go with "fall apart":

Things fall apart; the centre cannot hold;
Mere anarchy is loosed upon the world

Devolve.

Degenerate

Though there are definitely negative connotations here. Alternatively, just stick with Unravel. It's succinct, and less negative than alternatives.