According to psychologists, returning to an abuser is not unusual for victims of domestic violence. "I'm a human being and people put me on a very unrealistic pedestal. And all these expectations, I'm not perfect," she said.
"The thing that men don't realize, when they hit a woman, it's... the face, the broken arm, the black eye, it's going to heal. That's not ... the problem. It's the scar inside," she said. "You flashback. You ... you remember it all the time. It comes back to you whether you like it or not. And it's painful. So I don't think he understood that. They never do."
Shortly after the March trip to Miami with Brown, she realized she made a mistake and broke things off.
"The past few months, I just, I didn't talk about it to anyone, to no one. Not my friends. Not my family … It's not something that I wanted to relive. It's not something I wanted to think about ... I just put it away in a box...and just ignored it really."
The star, who has sold 15 million albums, -- is back after a nine-month hiatus with a new single, "Russian Roulette," from her highly-anticipated album "Rated R" to be released later this month.
"I feel when I look back on the four years, I feel like I've grown so much ... in such a short space of time and achieved a lot," she said. "I'm blessed."
The singer told Sawyer that she is not dating anyone now and can't imagine getting back together with Brown.
"I don't have a desire at all to be with him," she said. "... I can't see how we ... would get back together, but I'm also not God and I can't predict the future."
Rihanna decided to speak publicly about the incident to warn others who may be in danger of returning to abuse.
"I knew I had to do this in order to move on for me and in order for my fans to move on with me because it would always be a question in their mind," she said. "I don't want that five years from now every time they see Rihanna, they think of Chris Brown beating me. That's not who I am. It's just one thing that happened to me."
CLICK HERE for resources and information on how to help stop domestic violence among teens and young women.
Watch the full interview with Rihanna on "20/20" at 10 p.m. E.T. Friday, Nov. 6.
ABC News' Sheila Marikar contributed to this report.