Lisa’s mother Jean died at age 84 in England, RadarOnline.com confirmed.
Her rep confirmed her mother's passing, but said she's too upset to comment at this time.
“She’s absolutely devastated at losing her mother when she is still grieving over the loss of her brother,” the rep told Radar.
According to reports, the reality star has officially stopped filming after receiving the news.
She is also expected to fly to London from Beverly Hills soon to handle her mother’s funeral arrangements.
The news of her mom’s death comes a year after the RHOBH star's twin Mark committed suicide in April 2018.