Juelz Santana, the rapper who's collaborated with Chris Brown, Sean Kingston and Cam'ron, was arrested at his home in New Jersey -- after his wife told cops he threatened to kill her! Cops tell us they showed up at Santana's Teaneck home around 10:30 this morning after his wife called 911. According to law enforcement sources, James' wife did not need medical assistance -- but she told police the threat was made in front of a child. The rapper was arrested on domestic charges and is still in police custody. Story developing ...