Chynna Phillips is in rehab

Singer Chynna Phillips has entered rehab, her rep confirms to UsMagazine.com.

"After much thoughtful deliberation, Chynna Phillips has checked herself into an undisclosed treatment facility for anxiety," her rep, Lizzie Grubman, tells Us in a statement. "With the full support of her family and friends, she is looking forward to her recovery. We ask that people respect her and her family's privacy at this time."

Phillips, 42, was a member of '90s band Wilson Phillips. She has three children with her Gossip Girl husband, Billy Baldwin.

A source close to the singer tells Us that Phillips is still reeling from her half-sister's confession that she carried on a drug-fueled, incestuous affair with their father, John Phillips of the Mamas and the Papas.

"The whole thing has caused Chynna such stress she needs to rest because of it," the insider tells Us. "Mackenzie's admission took a toll on her and the whole family."

In an appearance with Mackenzie on The Oprah Winfrey Show last fall, Phillips said, "I pray that we all get closer through this crisis... But I would be lying to you if I didn't tell you that there are going to be some huge obstacles in front of us."

She dropped an album, One Reason, with Vaughn Penn last September -- one day before Mackenzie released her tell-all, High on Arrival.