Danity Kane -- We're Done

Danity Kane is no more ... TMZ has learned the group has broken up after a recording session turned violent.

TMZ broke the story ... Aubrey O'Day got sucker punched by Dawn Richard Monday. She says, "Sadness does not even remotely begin to describe what I feel right now."

Shannon Bex says, "I now must walk away feeling used and manipulated."

The group reunited in May of last year, but had nothing but trouble. Aundrea Fimbres bailed almost immediately and the girls just couldn't pull it together.

They had almost completed their new album, and it's unclear if it will ever be released.