After being challenged by cops he eventually confessed to ripping out Nemeth's intestines in a jealous rage.
Alongside the crime scene footage police also released video of Lopez's interrogation, CBS Miami reported.
"Fidel, this was not a case of rough sex," one of the detectives can be heard telling Lopez.
Later in the interrogation the detective advised him: "You have to do the right thing and tell the truth."
Lopez insisted that he loved Nemeth.
"She's a good girl," he said. "She's a perfect girl, man. She's my love."
Then, after hours of questioning, the suspect cracked, admitting that he lost his cool after Nemeth called him by her ex-husband's name during sex.
"She changed my name," he said. "She called me the name of the other (expletive) guy. And she said it twice and she was wrong and she was confusing me with him. At that point, I get mad," he said. "I get really, really mad."
According to cops Lopez admitted to becoming a "monster" and wrecking the apartment, then murdering Nemeth, originally from Peru.
The crime scene video shows the apartment's interior covered in blood.
The largest concentration of blood appears to be in the closet where detectives say the couple was having sex when Nemeth called out her ex's name.
Elsewhere in the video can be seen an open tequila bottle, sliced limes, a smashed sliding glass door and a hole in the wall.
Lopez, who was arrested shortly after the September 2015 attack, has pleaded not guilty to first-degree murder. He is being held without bond as he awaits trial. Prosecutors are said to be seeking the death penalty.