Rihanna acknowledged that Brown bit her and had her in a headlock until she had trouble breathing. She told Sawyer that she did not try to fight back.
"I fended him off with my feet from one ... side of the car, but ... it was not like, it was not like a fight with each other. I just ... I really just wanted it to stop," she said.
Her screams prompted someone to call 911 and report the disturbance to the Los Angeles Police Department. Rihanna told Sawyer that, by that point, she was "battered."
"I was bleeding. I was swollen in my face," she said. "So there was no way of me getting home, except for, my next option was to get out of the car and walk. Start walking in a gown, in a bloody face. So I really don't know what my plan was. I didn't have a plan. That whole night was not part of my plan."
To the shock of many fans, the two pop stars reunited after the assault -- a decision which Rihanna now calls a mistake.
"I went through ... a host of emotions. It was confusing for me. I was still attached by love. But I wasn't thinking about ... the reality of the situation," she said.
In denial, she said her love for Brown clouded her judgment. "I made a selfish decision for love. It was a wakeup call. ...Love is so blind. It is so blind.
"You start lying to yourself. ... This is a memory you don't want to have ever again. ... the physical wounds go away, you put it in the back of your head and you start lying to yourself subconsciously," she said. "I felt very lonely. ...I couldn't even go back to my own house because there were 200 people outside with cameras, paparazzi, journalists, fans, neighbors."
She told Sawyer that the media blitz was overwhelming and extremely isolating.
"This is why I made my decision. ...I felt really lonely. ...There were times when I cried. There were times when I just sat there all day and watched TV," she said.
Rihanna said she was "embarrassed" and "humiliated" by the graphic photo of her that was leaked to the press after Brown's attack, in which her face appears battered and swollen.
"Who likes seeing their face like that? ...I feel humiliated. I get angry, all over again, every time I see it," she said. "The whole thing plays back in my head. So I don't like to see it."
Rihanna told Sawyer that at the time, she even convinced herself that she had to protect Brown from scrutiny.
"If I feel this depressed, then what is he going through?" she said. "I had to protect him. I thought that I had to let him know, don't do anything crazy. Like just hang in there...The whole world hates him now. His fans, his career. He just, he lost me, I just need to let him know; don't do anything stupid ...I'm not saying that's an excuse for me to go back, but this is what I was thinking about."
The singer said she replayed the incident in her head, and began to question what she could have done to set off Brown.
"Initially you start thinking, what could I have possibly have said to make him hit me?" she said. "Eventually you're like, you know ... stop. Stop. Stop. Ask yourself. There's nothing you can do or say to make somebody do that to you. That's on them. And ... I just knew he had a problem. I knew he had a problem. He had a temper. He needed to get some help. And ... and he did."