A Staten Island woman claims she was defending herself when she fatally stabbed her boyfriend in the chest early Saturday morning.

Christina Quinones was arrested and charged with second-degree murder and assault after police found 31-year-old Ruben Jimenez wounded in her apartment. Jimenez was taken to Staten Island University Hospital, where he was later pronounced dead.

The stabbing took place at 1 a.m., and the couple's two sons, ages 4 and 10, were in the apartment during the incident, according to NBC. An NYPD spokesman told SI Live that the children did not witness the stabbing.

Quinones's family told the Daily News that Jimenez had "brutalized the young mom for years," and Saturday's stabbing reportedly stemmed from fighting over a phone call the man had received from another woman Friday night. Jimenez allegedly tried choking the woman before she picked up a knife and stabbed him.

"She was a single mother...a very good mother, but she was in an abusive relationship," one of Quinones's relatives told the tabloid.

Melissa Ortiz, a friend of Quinones and resident of the same apartment complex, described the accused as "a 24/7 mom who cared about her kids. Her kids were her life."

"This is scary. A man is dead — someone she loved," Ortiz told SI Live. "I don't know what happened. This comes out of nowhere." Police told the blog that Jimenez had previously been charged in two domestic incidents involving Quinones, including assault and obstruction of breathing in 2014.