Rihanna on Chris Brown Remixes: All About the Music!

When Rihanna tapped her abusive ex-boyfriend, Chris Brown, to join her on a sexually explicit remix of "Birthday Cake" last month, the music world was shocked.

Chatting with Ryan Seacrest on his radio show, she spoke about the reasons behind that remix and their other collaboration (on Brown's "Turn Up the Music").

"I reached out to him about doing 'Birthday Cake' because [he was] the only person that really made sense to do the record, just as a musician," Rih said.

"Despite everything else, that was gonna be the person."

"You know, I thought about rappers, [but] the hottest R&B artist right now is Chris Brown. So I wanted him on the track," she explained matter-of-factly.

In turn, she agreed to guest on his own remix, she said:

"It was a tradeoff. Two records - one for my fans, one for his fans. That way, our fans could come together. There shouldn't be a divide. It's music and it's innocent."

Brown violently assaulted then-girlfriend Rihanna in February 2009, but the two have rekindled at least a friendship since that point, with rumors of more.

He attended her birthday party last month, and there's been talk of the pair secretly hooking up despite his ongoing relationship with girlfriend Karrueche Tran.

Chris Brown and Rihanna collaborating musically ...