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A rep confirms to Gossip Cop that Chynna Phillips returned home yesterday from rehab, where she was dealing with anxiety.

“She’s home and doing great,” says Phillips’ rep, adding that the singer is celebrating her daughter Jamison‘s 10th birthday today. (Jamison is Phillips’ and Billy Baldwin‘s oldest child.)

Last year, Phillips’ half-sister Mackenzie Phillips claimed to have a longstanding sexual relationship with their father, John Phillips of The Mamas and The Papas. Chynna publicly supported Mackenzie while appearing on The Oprah Winfrey Show.

A little less than two weeks ago when Chynna Phillips checked into rehab, a source close to her told Gossip Cop she’s been “having a hard time since the summer, since [Mackenzie's] book came out.” The source added, “It’s been tough on her.” Gossip Cop was further told, “She’s really depressed,” and went to rehab “to figure out things” while receiving help for anxiety.

The same source explained Phillips “has a big heart” and was “trying to do the right thing” for her half-sister, but in retrospect felt some of what she said in support of Mackenzie wasn’t consistent with her thoughts on the matter.

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Chynna Phillips has entered a rehabilitation facility for anxiety, her representative confirms to Gossip Cop.

Last year, Phillips’ half-sister Mackenzie Phillips made waves by revealing a decade-long sexual relationship with their father, John Phillips of The Mamas and The Papas. Chynna publicly supported Mackenzie while appearing on The Oprah Winfrey Show.

But a source close to Phillips tells Gossip Cop she’s been “having a hard time since the summer, since [Mackenzie's] book came out.” The source adds, “It’s been tough on her.” We’re told, “She’s really depressed,” and “trying to figure out things” while receiving help for anxiety.

The same source tells Gossip Cop that Chynna Phillips “has a big heart” and was “trying to do the right thing” for her half-sister, but in retrospect feels some of what she said in support of Mackenzie wasn’t consistent with her thoughts on the matter.

Phillips has three children with husband Billy Baldwin.

Follow @GossipCop on Twitter for the latest in accurate celebrity news!

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UPDATE – 10:18PM

“I had sex with my own father.”

Mackenzie Phillips will reveal tomorrow on Oprah that her father, Mamas and Papas founder John Phillips, raped her, Gossip Cop has learned. The interview coincides with the release of her memoir, “High on Arrival.” Already it’s been revealed in promos for tomorrow’s program that her father introduced the “One Day at a Time” star to drugs. She recalls, “My father shot me up for the first time.” She also discusses Mick Jagger‘s attempt to seduce her and other long-held secrets.

But the most stunning revelation is that John had sex with a drugged-out 19-year-old Mackenzie as she faded in and out of consciousness on the eve of her wedding to Jeff Sessler in 1979. According to a leaked copy of the book, when she later confronted him about it, she said, “We have to talk about how you raped me,” to which he responded, “You mean when we made love?” The two had a long-term incestuous relationship, the memoir reveals.

Earlier this afternoon Oprah tweeted, “Interviewed One Day at a Time’s Mackenzie Phillips. Thought I’d heard it all … beyond shocking! We’re airing it Wednesday.”

We contacted Harpo Productions, and they did not get back to us. We also exchanged a series of e-mails with Simon & Schuster, the memoir’s publisher, explaining that we had heard the book’s big secret was that Mackenzie and John Phillips had a long-term sexual relationship. We have now confirmed it.