A backup guard for the Boston Celtics threatened to kill himself in a text message to his 20-year-old girlfriend after she escaped four hours of physical torture in his Brighton apartment, according to police reports released yesterday.

Jabari C. Bird, 24, the Celtics’ second-round draft pick last year, was ordered held on $100,000 bail, which Brighton District Court Judge David Donnelly split into $50,000 cash and $50,000 surety — the latter due only if Bird goes on the lam.

“Unless you’re a drug dealer, you don’t have $100,000 lying around!” Bird’s attorney Brian Kelly protested to Donnelly.

Bird was released yesterday afternoon after a $50,000 cashier’s check was posted. He pleaded not guilty to strangulation, kidnapping and assault charges. Donnelly ordered him to return Oct. 25 for a pretrial conference.

Bird’s accuser claims Bird strangled her 12 times after a quarrel, threw her against a wall, dragged her around by the ankles, kicked her and held her against her will for four hours Friday afternoon, later texting her that he would kill himself if she didn’t come back, according to court documents.