Collins said he had only ever slapped Ms Larke to calm her down when she was self-harming, which he claimed she did, once gouging her wrists and threatening to commit suicide.
Saying "she had a screaming fit" during a relapse in the hotel room, he said: "She would have episodes and I would try to calm her down.
"She was saying 'You are going to hit me, you are going to hit me', and I was saying 'What are you talking about?' I have never hit anyone in my life. I don't know where what she was saying comes from. A man came to the hotel room to ask if everything was all right."
Collins, who shot to fame with The Friday Night Project, denies harassing Ms Larke, a former video games public relations worker. Collins said he spent £25,000 on Ms Larke during their relationship, "a ridiculous amount of money".
The prosecution has alleged that Collins, who met Ms Larke and began an extra-marital affair with her in 2006, made her write down every sexual experience she had ever had. The court heard that in Collins's police interview, he said it was her idea as she had a "chequered colourful history" with sex and drugs and she "wanted to offload".