Carlos Delposo told police he stabbed his former wife after overhearing her talking to another man.
Delposo, 27, of 3207 Navajo Dr., is charged with attempted first-degree murder and aggravated domestic assault.
Yessica Ruiz, 29, was in critical condition after the incident on Monday in Brainerd.
Police found her lying on the ground covered in blood. Officers found that Delposo was bleeding from his right leg.
He later said he was in the bathroom when he overheard her talking to the other man. He said he got a knife and went to confront her. He said he began hitting her while trying to get a cell phone away from her.
He said he injured his leg when he fell while running from the scene.