Deviant doc Larry Nassar whined he's an "innocent person" in the caged sex creep's first sulky message from behind bars — where he's rotting for molesting innocent American gymnasts in a decades-long campaign of sickening abuse.

Breaking Celebrity News has exclusively obtained a letter from the former USA Gymnastics team doctor, dated May 11, in which the twisted perv shamelessly walked back on his apology to his more than 250 innocent victims — and griped about being railroaded for his disgusting crimes.

"When an innocent person is forced into a guilty plea, the world is set on fire," the 54-year-old disgraced doctor declared in the handwritten, one-page jailhouse rant.

As Breaking Celebrity News reported, the manipulative molester, who was already doing 60 years hard time for child [expletive] crimes, made a lame mea culpa in a Lansing, Mich., courtroom before he was slammed with 175 years in the clink for sexual abuse in February — after being bravely confronted by 156 of his traumatized victims.

But his disturbingly tone-deaf letter reveals Nassar now believes he is the victim.

"People that support that innocent person before, turn against, feel betrayed, feel hurt because they trusted that person," he wrote of the young athletes who condemned him at his trial.

In a shocking courtroom showdown, dozens of shattered gymnasts, who had entrusted Nassar with their health, lined up to release their fury over the doctor's betrayal before a judge locked him away for life.

"You lied to me and manipulated me. You are so sick," spat Olympic gold medalist Aly Raisman, now 23, at the trial.

McKayla Maroney, an Olympic champ in 2012, said: "