"I was wrong for what I did," Brown told ABC News' Robin Roberts. "And I would definitely say that it's not something that I look past or look over. Something that's really, really touchy. And, and like I said, I'm -- I'm really sorry for -- for what went down. And what happened."
Brown, 20, spoke candidly to Roberts about his year-long relationship with pop sensation Rihanna, which began as a friendship.
Brown -- then a 15-year-old skinny teen with a winning smile -- had rocketed to the top of the Billboard charts and was hailed as the next Michael Jackson. The prince of R&B and 16-year-old teen pop queen Rihanna had a seemingly fairytale relationship. But something disturbing emerged.
Brown beat Rihanna during an argument after a pre-Grammy Awards party Feb. 8, 2009.
"I never ever had problems with anger. No, no domestic violence with any of my past girlfriends or any altercations," Brown said. "I never was that kind of person. ... I look at it, and it's really, like really difficult. It's like, 'How could I be that person?'"
According to the police affidavit, the argument began when Rihanna read a text message on Brown's phone from another woman. Brown shoved Rihanna into the window of his car, while driving. According to the police report, he punched her several times and said, "I'm going to beat the s**t out of you when we get home." When Rihanna countered by calling her assistant's phone, Brown warned, "You just did the stupidest thing ever. I'm going to kill you," and threw her phone out the window, the report noted.
Brown, who fled the scene, turned himself in to police eight hours later and was charged with two felonies, assault and making criminal threats. He was released after posting $50,000 bail, but faced a firestorm of controversy.
"It was something that -- I really have to really think about it. I was like, 'Man, I let a lot of people down,'" he said.
In the fallout from the assault, advertisers for the Milk Mustache campaign and Wrigley's Doublemint gum dropped the singer. Some music stations across the country also banned Brown's songs.
Brown's YouTube Apology Was Heavily Coached
But it was the public apology he posted on his YouTube page, six months after the assault, which drew some of the sharpest criticism. In a video, Brown apologized to his fans, claimed to have apologized to Rihanna "countless times," and reiterated that he was seeking help.
"I take great pride in me being able to exercise self-control, and what I did was inexcusable. I am very sad and very ashamed of what I've done," he said, speaking directly to the camera. "I intend to live my life so that I am truly worthy of the term 'role model.'"
In Rihanna's exclusive interview with Diane Sawyer, which aired on "20/20," Rihanna said it sounded like Brown "might have been reading off of a teleprompter."
Brown revealed to Roberts that he had been heavily coached.
"I had a week of -- not -- not even a week, maybe three or four days of PR. And they just telling me like, 'OK, don't say this. And don't say it this way, 'cause they're gonna take it this way,'" he said. "So, I had in my -- my head wasn't really giving me a chance to be me. It was just being myself through other people. ... It was genuinely from me, but it wasn't projected genuinely."
Brown Reacts to Rihanna
Brown also reacted to Rihanna's comments from her exclusive interview with ABC News' Diane Sawyer, when the pop star broke her silence about the night Brown beat her.
"I know that he felt really bad about doing it. I just didn't know if he understood the extent of what he did," she said in the "20/20" interview. "The thing that men don't realize. When they hit a woman, it's -- the face, the broken arm, the black eye. It's gonna heal. That's not the problem. It's the scar inside."
Brown told Roberts he understood Rihanna's remarks about the wound that does not heal.
"I can, I can see what damage it does, mentally, more than physical," he said.
Brown has talked about domestic violence in his own family. On the "Tyra Banks Show" in 2007, he talked about the abuse his mom suffered from his stepfather, who has always denied the charges.
"He forgot the pain that he witnessed with his mom. Fame came to Chris very, very young. At a very young age, so with fame comes a lot of things and the most dangerous thing is the freedom. No limits. No boundaries. You're a kid and the word 'no' doesn't exist," Rihanna said.
Brown said it was difficult to hear his former lover's remarks.
"It's really difficult. ...And it kind of -- it hurts. But it's just -- it's just something that I have to be responsible for, because I'm responsible for my actions," he told Roberts.
Brown, 20, pleaded guilty to felony assault and was sentenced to five years of probation, community labor and one year of domestic violence counseling. He said the classes have helped him control his emotions.
"In this class, I'm not saying necessarily teaches you how to love, but like those emotions that get mixed up when you just in love or just whether it's jealousy, insecurities, whatever the case may be in -- in relationships. They teach you how to control a lot of -- certain things," he said.
'Changed Man': Brown Says Rihanna Heard Song and Cried
The couple briefly reunited three weeks after the assault in Miami and Brown wrote the song, "Changed Man," for Rihanna as a plea for forgiveness. The lyrics refer to the turmoil that struck their relationship.
"What do you do when the truth isn't quite enough/ They looking at you telling you that we need to break it up/ You need to do what you do, it's me and you in love/ But I'mma make it up to you and show the world I'm a changed man," he sings.
While Rihanna said that she has not heard the song, Brown told Roberts that he played it for her a month after the incident and she cried.
"I played the song for her. ...The day I did it...a month after the situation," he said. "She called when she first heard the song. And I mean, I'm not trying to say -- call her any liar or anything like that. But I played the song for her when I first wrote it. And she cried."
Brown Focuses on Future
The couple officially broke things off in March 2009. A restraining order requires Brown to stay 100 yards from his former girlfriend for the next five years, unless they are attending music industry events.
Brown told Roberts that he still has "love for" Rihanna, but there are no words left.
"I've said like everything that I can with me and her. Me and her have talked. Me and her have spoken about the situation," he said. "And she knows how sorry I am."
Despite the public scrutiny, Brown said it has made him into a stronger man.
"I think just being -- I would say ridiculed, but just criticized and -- and scrutinized by a lot of people. And just being able to see who I am as a person, it just shaped me to be a more stronger and -- better young, black male," he said.
Now, though some fans believe his music is tainted by the assault, Brown said he's focusing on his craft. His new album, "Graffiti," is set to be released Dec. 8.
"I really just -- just try to -- try to focus on what it is that I can do as far as my talent. ...and really show people what they fell in love with me for. And just really kind of give them -- give them all of me back," he said.
Watch the full Chris Brown interview on "20/20" tonight at 10 p.m. ET.
ABC News' Sheila Marikar and Luchina Fi