June Steenkamp called Oscar Pistorius a "devil" and said she does not care if the runner is sent to prison for killing her daughter Reeva as nothing will bring her back.
"He has an aggressive persona, he's used to having people adore him, so it must be pretty different for him now," said Steenkamp.
"He's been spoilt by other people, that's why he struts around and looks superior.
"He's gone from hero to devil."
The pain of losing her daughter Reeva Steenkamp is so great that not even Pistorius going to jail for decades if convicted would make her feel better, said the 67-year-old.
"I don't care what happens to Oscar, I don't even care if he goes free. All I know is that he has to stand up to what he's done and – if he has to – pay for it.
"What difference is it going to make to me if he goes to prison for 25 years or is allowed to walk free?
"No one can tell me how I should feel, and those are my feelings.
"I'm not a person who wants to punish him. I want my daughter back, but it's never going to happen," Steenkamp told the Mirror.
June Steenkamp has watched Pistorius give evidence all week and her impassive demeanour has cracked only rarely - including when an image was flashed up of Reeva's devastating head injury.
"I keep it all in and when I get back to the hotel it all comes out and I break down," she said.
"I start crying out, crying all the tears and pain I've held inside in court. I feel very vulnerable.
"The whole world is watching you and you don't want people to see you when you're in pain.
"I don't want to be crying in public. I'm a private person. I like to keep my feelings to myself.
"I'm being strong for Reeva, I have to be there. It's hard for me to do it, but I'm representing my child."
Pistorius denies murder and claims he mistook Steenkamp for an intruder. The prosecution alleges he killed her following an argument between the couple.
The trial continues.