The 38-year-old husband of Bay Shore resident Monica Paul was arrested and charged with second-degree murder.
Officers responding to a 911 call from the husband found Paul's body at her apartment on Saturday night. Her husband was arrested and treated at a nearby hospital for injuries he received during a struggle with his wife.
The couple's son was playing outside during the fight.
Suffolk Police Detective Lt. Gerard Pelkofsky says Paul was stabbed after the couple got into an argument over visitation.
The couple separated in May.