A Roxbury teen changed her plea to guilty in Suffolk Superior Court on Wednesday, and will serve up to 14 years for fatally stabbing one woman and wounding another juvenile in a fight over a leaked sex tape.

“Everything about this case is tragic: The loss of one young woman, the serious injury of another and the conviction and incarceration of a third,” said Suffolk DA Kevin Hayden. “The combined elements of youth, impulsiveness and social media weaponization forged an incident that ended one life and forever altered many others.”

Wilmary Mejia Matos, 18, pleaded guilty to the manslaughter of 21-year-old woman Brianna Brown and assault and battery with a dangerous weapon causing serious bodily injury for the non-fatal stabbing of a 17-year-old two years ago.

Matos, tried as an adult due to the serious nature of the charges despite her age, originally pleaded not guilty to murder during her arraignment days after the deadly altercation.

Matos was sentenced to 10 to 14 years in prison, followed by three years on probation.

On Feb. 11, 2023, 16-year-old Matos learned her boyfriend at the time “videotaped them having sex and sent the video to the 17-year-old victim,” the DA’s office said. The defendant said she believed the teen had posted the video online and confronted the victim over social media, where they “exchanged threats.”

The situation escalated, and the pair agreed to meet at Woodside Avenue in Jamaica Plain to fight, the DA’s office said.

Matos reportedly came with two male friends — sending “threatening voice texts” and sharing her location — while the 17-year-old showed up with her brother and his girlfriend, Brown. One of the defendant’s friends tried to dissuade her.

The ensuing fight was partially captured on video, the DA’s office said. During the altercation, Brown was stabbed 16 times. The juvenile victim was stabbed four times.

Both victims made it to a local police station, according to police records, and taken to a hospital. Brown was pronounced dead at the hospital from wounds to her throat and chest. The teen was treated for serious injuries but recovered.

Matos was also taken to a hospital and treated for an abrasion to her forehead and cuts on both her hands and wrists, which prosecutors said were consistent with wielding her knife.

The defendant was found after the incident at a construction site with her boyfriend, and police located the knife believed to be used nearby.

Family members of both victims were present in court on Wednesday and gave emotional victim impact statements during the hearing.

One of Brown’s brothers said his sister’s life was “that of a dandelion, beautiful and fleeting. Here one day, gone the next.”

“If I learned one thing from my sister, it’s how to forgive,” Brown’s brother addressed to Matos in court Wednesday. “I forgive you.”

Hayden said, “It’s the saddest of situations for all involved, and a sad situation for the city itself.”