Lisa Vilate Williams was making homemade ornaments with her boyfriend’s twin three-year-olds at his apartment on Sunday when his ex-wife, Chelsea Watrous Cook, 32, burst in and shot her to death in front of the children, police said.
The slaying came after Cook targeted the 26-year-old with online bullying, in-person confrontations and harassment for months, her sister and mother revealed.
‘I worried for her safety every day,’ said her mother, Tawny Williams.
Related: Utah high school teacher ‘shoots and kills ex-husband’s girlfriend’ in front of the former couple’s three-year-old twin daughters! Chelsea Watrous Cook, was arrested Sunday night in Salt Lake City

Chelsea Cook was arrested on suspicion of aggravated murder after her ex-husband took the gun away and pinned her to the wall until police arrived, authorities said.
Lisa Williams was transported to hospital where she died.

Chelsea who allegedly went to her Travis Cook’s home to give one of their three-year-old twins cold medicine, had locked herself in a bathroom when her ex Travis, asked her to leave.
She eventually emerged from the bathroom, whipped out a gun from her coat, firing several times at Williams while the children watched.
26-year-old Williams was pronounced dead when she was rushed to the hospital.
The Health teacher was charged with aggravated murder after her ex-husband took the gun away and pinned her to the wall until police arrived, authorities said.
The slaying came after Cook targeted William with online bullying, in-person confrontations and harassment for months.
After the shooting, her ex-husband Travis  told police that Chelsea Cook sat in a recliner chair near their daughters and watched as he tried to help his injured girlfriend.

Bekah Williams said she reported the behavior and use of school phones to the principal at Skyridge High School in Lehi in August: ‘it seemed that nothing was done, she said.
Alpine School District officials apparently weren’t aware that Chelsea Cook had been arrested Oct. 16 on suspicion of domestic violence. She had failed to self-report such arrests to their superintendents within 48 hours, as required.
The state also flags arrested teachers though a fingerprint database, but it was a misdemeanor case and her prints weren’t flagged for more than a month. The notification came through after her murder arrest.
‘It took a lot longer than we would hope,’ a school district spokes person said.

Victim’s mother, Tawny Williams who described her daughter as ‘kind, sweet, generous’ and ‘loving’ called Lisa’s killer a monster

Details of the domestic violence arrest haven’t been made public, but Bekah Williams said it didn’t involve her sister.
Lisa Williams was reluctant to report Chelsea Cook’s behavior to police, worried that involving authorities could make the situation harder on the children, her sister said. Looking back now, she wondered if that was a mistake.
‘In hindsight, I think the best thing for the kids would have been to call the police every time,’ Bekah Williams said.

They hadn’t had contact in the days before, since she was with her family for the Thanksgiving holiday.
Lisa Williams had moved to American Fork, south of Salt Lake City, a few years ago to care for her sister, who was hospitalized with a potentially life-threatening lung ailment. She’d stayed after the recovery, living with two of her sisters.
In the end, it’s that kind of caring for others that Lisa Williams’ family hopes she is remembered for.