The gay singer from "Nick & Norah's Infinite Playlist" didn't just brutally attack his real-life GF before his double arrest in December ... he also destroyed her bedroom and threatened multiple times to kill ... this according to the police report obtained by TMZ.
Rafi Gavron's GF told cops, the December 14 argument was triggered by Rafi's cocaine problem -- he demanded money from her and she refused ... so he went ballistic.
The GF said she hid her money and credit cards in her bedroom. In retaliation, Rafi punched her with both fists and slapped her across the face several times, then pushed her to the ground and kicked her in the stomach.
The GF says it wasn't over ... Rafi destroyed her bedroom, ransacking her dresser and closet and then kicking her mirror, breaking it. When she tried to phone police, she says Rafi grabbed her phone, threw it on the ground, shattering it to pieces, and repeatedly threatened to kill her.
The girlfriend says she managed to escape and ask a neighbor to phone police ... but Rafi took off in her car. She was taken to a nearby L.A. hospital with minor injuries, including marks on her legs and back.
As we reported, Rafi was subsequently pulled over in his girlfriend's car and arrested for DUI. Hours later he was released from jail hours and immediately arrested AGAIN for domestic violence.
He was charged with 4 felonies ... dissuading a witness from reporting a crime, false imprisonment by violence, domestic violence and joy riding. He copped a plea and pled no contest to domestic violence and joy riding. He was placed on 5 years probation.