Troubled beauty Mischa Barton has been so depressed she’s threatened suicide, even saying she’d kill her beloved dog, according to gossip blogger Janet Charlton.

Pals say the 20-year-old star’s life has been spiraling out of control since leaving “The O.C.” — and she was recently photographed sobbing, with bandages on her wrist.

However, Mischa’s publicist Dominique Appel denies that Mischa was suicidal or had threatened her dog. Appel told The ENQUIRER that “the bandaged wrist was the result of her accidental encounter with a broken glass.”

But a source told The ENQUIRER: “She’s in a bad place right now.”

And celebrity blogger Janet Charlton quoted a source on her Web site, saying: “Since she left ‘The O.C.’ she feels like everything is going downhill and her life is over.”

According to the Web site, Mischa’s boyfriend, singer Cisco Adler, 28, “couldn’t take the drama” and told her they’d be better off apart.

He told friends: “She’s too crazy for me,” according to Charlton’s posting at www.janetcharlton.com. “She threatened to leave if he didn’t give her a ring. He wasn’t ready to get engaged, so he stalled by buying her a ‘promise’ ring.”

The Web site says that Mischa was placated for a few weeks, but she soon started “acting crazy and hyperemotional again.”

“Cisco feels bad, so he’s pretending to work things out with her,” according to the report.

“He’s hoping she’ll come to her senses and won’t do anything violent or vindictive &#151 but he wants out.”