Chris Brown and Rihanna on stage in 2008.

Chris Brown and Rihanna on stage last year. Photo: Reuters

Rihanna has opened up to Oprah Winfrey about the assault that ended her romance with Chris Brown, confessing she felt humiliated and embarrassed after the singer beat her up on the eve of the 2009 Grammy Awards.

Both stars pulled out of their planned performances at the music gala at the last minute after the bust-up and Brown was later charged with assault.

He publicly apologised for his actions, which left the Umbrella singer sporting a black eye and swollen lip, and was ordered to serve hard labour and probation.

Brown was also told he had to keep his distance from his ex, but that restraining order was lifted last year, allowing the pair to get together in the studio and record two new tracks.

In a candid new interview for Winfrey's Oprah's Next Chapter show, which will air in the US on August 19, Rihanna admits the drama following her fight with Brown put her in a very dark place.

She explains: "It was embarrassing. It was humiliating. I lost my best friend. I was resentful. I held a grudge. I was dark."

Rihanna, meanwhile, has risen to the top of a list of social networking superstars.

Editors at Forbes magazine have named her their internet queen, with 23.8 million followers and 59.6 million fans.

Lady Gaga, who is also an avid tweeter, is a close runner-up with a 28-million strong Twitter following and another 53 million Facebook fans, while rapper Eminem comes third with 11.9 million Twitter followers and 60.3 million Facebook fans.

Singers Justin Bieber (26 million Twitter followers, 45.8 million Facebook fans) and Katy Perry (24.5 million Twitter followers, 45.7 million Facebook fans) round out the top five.