Sandra Oh, who plays Meredith Grey's best friend Cristina Yang on ABC's Grey's Anatomy, will leave the medical drama after the upcoming 10th season, she told The Hollywood Reporter.

The actress has played the moody doctor since the series premiered in 2005 and will exit ABC's drama to instead pursue other opportunities. Oh was among the stars who signed new two-year deals in May 2012 to return to Grey's through season 10, including Patrick Dempsey, Ellen Pompeo, Justin Chambers, James Pickens Jr., and Chandra Wilson. She said she began thinking about leaving the medical drama back in May 2012 when what she called the "original six" signed their two-year deals.

"Creatively, I really feel like I gave it my all, and I feel ready to let her go," Oh said of her decision to exit at the end of season 10. "It's such an interesting thing to play a character for so long and to actually get the sense that she wants to be let go as well. [Cristina] wants to be let go, and I am ready to let her go. We have to start the process, story-wise, for the Grey's writers to think of why she's going to go."

"I've gone through a lot of therapy over this," she said through tears, talking about why she is leaving the show. "I started thinking about it because I had to prepare myself. I gave myself two years to emotionally let go. At the end of last season, [Grey's executive producer] Shonda [Rhimes] took me aside and said, 'What are your thoughts?' I said, 'I'm ready.' "

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Oh told her co-stars about her upcoming exit during Tuesday's table read for the show's 200th episode and said the decision "doesn't feel real" yet.

Cristina Yang -- a driven doctor who is known for putting her professional life over her personal affairs and for being Meredith's "person" - was the second character Rhimes created following Pompeo's lead character, according to the report. It's unclear how Oh's exit will be portrayed on-screen and how Rhimes will end Cristina's on-again, off-again relationship with Owen Wilson (Kevin McKidd). Season 9 ended with Cristina asking Owen if a life with her but without any children would be enough for him, after he bonded with young Ethan and given her desire to not have children. She ultimately decided for him that she would never be enough, and Cristina walked away from the relationship once again.

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Oh received five supporting actress Emmy nominations for the Grey's role. She is a four-time Image Award nominee, two-time People's Choice Award nominee and won a Golden Globe in 2006. Oh also took home the SAG Award for Actress in a Drama Series in 2006.

"I want this to be a celebration," Oh said of Cristina's final season on the show. "I want us to get to that point where we see this character ride off into the sunset. Letting go of such a huge part of my life ...

"I want to cry right now. Grey's has been the most important role of my life," she added. "Playing Cristina and growing her and growing myself in her, I want to usher her into the next section of her life in the best way possible. It's got to be Cristina Yang's happily ever after."

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