Speaking to the chat show legend for a new episode of Oprah's Next Chapter, the pop princess says: "It was embarrassing. It was humiliating. I lost my best friend."
And talking about the aftermath of the split, back in 2009, she continued: "I was resentful. I held a grudge. I was dark."
A short trailer for the show has been posted on the internet, revealing some of the questions that Oprah asks but not Rihanna's answers.
These include "Do you think Chris Brown is a true love for you?" and "Where does your relationship stand today?".
Talking about stardom, Rihanna admits she is "super duper afraid of the pedestal that comes with fame", and says: "It's amazing how lonely you can feel."
The show will be broadcast in the US on 19 August.
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