Johannes Jacobus Steyn, dubbed the "Sunday Rapist", said on Thursday the forgiveness he asked for in a statement was for cheating on his wife.
He was testifying in the High Court, sitting in the Palm Ridge Magistrate's Court in Alberton.
Prosecutor Carina Coetzee was questioning him on an incriminating statement he made to a magistrate in Krugersdorp two days after he handed himself over in October 2011.
In it he admitted to phoning his wife, her mother, a pastor, and a psychologist and asking for forgiveness.
In these phone calls, he referred to himself as a "monster" and said he wanted to stop.
However, he maintained this was because he cheated on his wife with prostitutes and other women, and because of his addiction to pornography.
He also wanted to "make things right with God".
Steyn is accused of murdering school girls Louise de Waal and Lazanne Farmer.
He is also charged with 11 counts of rape, 10 of sexual assault, 10 of kidnapping, one of attempted sexual assault, one of attempted kidnapping, and two of assault.
The 11 girls Steyn allegedly attacked between 2008 and 2011 were aged between 11 and 18.
The 36-year-old pleaded not guilty to all 37 charges against him on Monday.
Asked by Coetzee if he was not emotional at being charged for the murder of a child, he answered: "It was of concern to me, but not so emotional".
Coetzee asked Steyn why he attempted suicide before handing himself over to police.
"I'd rather die before I'd be locked up again. And with the uncertainty because of my previous conviction, and at that stage I was emotional."
Earlier on Thursday, he testified he wanted to hire a prostitute the morning of de Waal's murder.
"I went looking for a good time... I went to find a prostitute... to get something I don't get at home."
When Judge Sita Kolbe asked further about this alibi, he said it was "very early" in the morning.
Steyn was testifying on what police told him prior to an incriminating statement he made to a magistrate in Krugersdorp. He said he admitted to crimes he did not commit because he had a previous conviction.
"Take the punch... because you won't get out of this... go on with your life... this is the easy way out for you," he said police told him.
He said investigating officer Peet du Toit briefed him on what to say before making the statement to the magistrate.
"I was told I was young. Plead guilty and go on," a calm Steyn told the court.
Coetzee asked Steyn how he could have found police actions against him threatening.
"They scared me into talking," was his answer.
Kolbe ruled the incriminating statement would be admitted into evidence.
"The confession is admitted into evidence at this stage. This ruling may be revisited at a later stage."
She would give the reason for her ruling later.
De Waal's mother Shereen told reporters she hoped her daughter would become an icon. She said attending court proceedings this week had been difficult.
"I am on medication. My nerves are shot, but I have to be here for my daughter. I have to be here for Louise."
The part of the trial involving De Waal would conclude on Friday with testimony from her sister Jessica.