As Nodarse was questioned by the defense, he described his mental state as between "reality" and "nightmares" during the murders.
"When I pulled the trigger, I did not know that was reality," said Nodarse.
The defense attorney used the unloaded gun in court Friday as evidence.
Nodarse pleaded guilty but mentally ill to one of the three murders, and on Friday he testified about his drug use, mental illness and paranoia.
Nodarse says he committed the murders because he was worried that if he didn't, Borizov would come after his own family.
"I was convinced by Mr. Borizov that there were two possibilities that would end this situation. One being the Kramer family being killed, and the other being my family being killed," Nodarse said.
Nodarse says Borizov planned the murders because because he hated the Kramers, who were his ex-girlfriend's family. Borizov was in a custody battle at the time with the Kramer's daughter Angela.
The Borizov case is the first murder trial to be televised in the Chicago area.