Piper survived a rape and acid attack in 2008 which left her facially disfigured.
A copy of the book was discovered by police in Leong's room, the court was told.
Rotariu told the court he believed the attack - allegedly carried out by Mark Cummings - was "revenge" for "stealing" Leong, 51, from Cummings, 46.
He described the moment acid was poured over his face, chest, arms and hands, saying he thought it was 'boiling water'.
The court also heard how Rotariu- who was in a relationship with Leong and previously lived with Cummings - tried to protect his face with his hands, but his attacker pulled them away.
In his initial police interview Rotariu described having an argument with Leong when he got home from work, telling officers he was upset and told her to leave him alone.
He went to bed at about 8pm and woke up as someone took the cover off his bed and splashed him with a liquid.
Referring to a statement previously given by Rotariu, Leong's barrister, Judy Khan QC, said: "You said: 'I was protecting my face with my hands.
"He touched me a little bit, he tried to pull my hands away from my face.
"It felt like boiling water, that's how it felt.
"I don't know who it was exactly, if he was a man or a woman I cannot tell, it felt like it was a man.
"I was thinking I was dreaming when I opened my eyes, so I closed them back.
"I don't know who it was exactly, if it's a man or a woman. It was like a man, how he was reacting."
"My eyes started to go like fog. I went to the bathroom, I screamed."
Both Cummings, from Leicester, and Leong, also from Leicester, deny attempted murder and a separate charge of intentionally inflicting grievous bodily harm.
The court previously heard how Cummings was recruited by his ex Katie Leong to launch the attack on July 27 last year.
Leong and Cummings dated until 2015, and by December 2015 Leong and Mr Rotariu were in a 'deep relationship'.
Judy Khan QC added: "When asked why [you thought Mark Cummings did this to you], you said it was a long story.
"You said Mark wanted revenge because he loved my girlfriend [Leong] but she's my girlfriend and he loved her."
The trial continues.