To break down crying; to sob uncontrollably to the point of collapsing or sitting down in despair.
彼女は母の訃報を聞いて駅のベンチで泣き崩れた。
She heard about her mother's death and broke down in tears on a bench at the station.
試験に落ちた子が教室で泣き崩れていたが、友達が落ち着かせた。
A child who failed the exam broke down crying in the classroom, but friends calmed them down.
あまりの悲しさに彼は声を上げて泣き崩れるしかなかった。
He had no choice but to break down crying aloud from such sadness.