In previous sessions of the trial, Gisèle said she had been worried she was developing Alzheimer’s or a brain tumour because of hair and weight loss and large memory gaps. These were, in fact, side-effects of the drugs her husband was giving her.
"I tried to stop, but my addiction was stronger, the need was growing," he said.
"I was trying to reassure her, I betrayed her trust. I should've stopped sooner, in fact I should've never started at all."
Mr Pelicot is also accused of drugging and abusing his daughter, Caroline, after semi-naked photos of her were found on his laptop. He has previously denied this and on Tuesday he also stated he had never touched his grandchildren. "I can look my family in the eyes and tell them that nothing else occurred," he said.
Mr Pelicot also said he "became perverted" when, in 2010, he met a male nurse on the internet who suggested he drug his wife with a sedative, explained how to administer it and shared photos of drugged women. "That's when it all clicked," Mr Pelicot said. "Everything started then."
In one section of Tuesday's hearing, Mr Pelicot was also asked about the thousands of videos he filmed of men abusing his unconscious wife. These were found by investigators and were instrumental in tracking down the 50 men who are now accused of rape.
Mr Pelicot recognised he had filmed the men partly for "pleasure," but also "as insurance".
Throughout the morning, Mr Pelicot appeared determined to rebut one of the main lines of defence of several of the accused, which hinges on the premise they did not “know” they were raping Gisèle - in other words, that they thought they were having consensual intercourse with her.
Mr Pelicot met the defendants on a chat room called "Without her knowledge" on a now-closed website which hosted pornographic material.
"I didn't force anyone, they came to look for me," he said on Tuesday. "They asked me if they could come, and I said yes. I never handcuffed and dragged anyone."
Some have said they were "manipulated" by Mr Pelicot into believing they were taking part in an erotic game in which Gisèle was only pretending to be asleep because she was shy, and several denied they knew they were being filmed.
But Mr Pelicot said the only person he ever "manipulated" was his wife, and also said that the men must have known they were being filmed: "There was a tripod and a screen attached to it, everyone could see it as soon as they walked into the room."
Mr Pelicot said he wanted to prove that his wife "was a victim and not an accomplice. To prove that everything happened without her knowledge. I'm aware many [defendants] have disputed this."
Béatrice Zavarro, Mr Pelicot's lawyer, told French TV that she did not know what people would think of her client, but that he was "sharing his truth".
She added that Mr Pelicot was "very downtrodden" and that although she did not know what his wife would make of his request for forgiveness, "the confession is now under way and he will continue."
She said: "We will get to the end of this trial and we will know everything about Dominique Pelicot."
Mr Pelicot, who was diagnosed with a kidney infection and kidney stones, was absent from court for nearly a week because of illness. He is set to give his testimony throughout the day, although he will be allowed frequent breaks.