AceShowbiz -

Tallulah Willis, the daughter of Demi Moore and Bruce Willis, has entered rehab. "Tallulah was pretty much given an ultimatum," a family insider opened up to PEOPLE. "Her parents were about to take away everything from her."

Tallulah reportedly checked into a treatment center, The Meadows, in Arizona in late July to seek help for her alcohol and cocaine issues. The 20-year-old fashion blogger did post a cryptic "bai bai" message in one of her last tweets on July 23.

A source claimed she was "adversely affected" by her parents' divorce in 2000, while her former classmate in high school said she was struggling to cope with her mother's hospitalization and subsequent rehab stint in 2012.

"When Demi was hospitalized, Tallulah didn't show up to school for days because she was too embarrassed," the friend says. "She was very open about Demi's issues and would sort of imply, 'Of course I have issues too, look at my mom.' "

Meanwhile, Tallulah herself discussed her insecurities about her looks during a chat with StyleLikeU earlier this year, saying she had been diagnosed with body dysmorphia. She seemed "lost," another source said. "The constant and self-centered worry over her looks mirrors her mother."

Moore and Willis have visited Tallulah at the rehab, but they have different approaches to their daughter's issues. "If Bruce suspected that Tallulah had any kind of substance abuse problem, he would have demanded for her to get help," a Moore source said. "Demi's take is that Tallulah is still very young and trying to find herself."