Sherrone Moore‘s former assistant is breaking her silence after the coach’s stunning downfall … claiming he had “complete control” over her during their secret affair and used that power to keep her trapped.

Paige Shiver sat down with ABC News in an interview set to air Friday during “Good Morning America” and didn’t hold back … saying Moore manipulated her emotionally and professionally throughout their relationship.

“Here’s a man that had complete control over me, over my emotions, over my career — and he knew that, and he used it, he used it against me,” Shiver said.

As we reported … Moore was fired as head football coach by the University of Michigan in December after Shiver handed over evidence of their affair to school officials and ended what the school deemed an “inappropriate relationship.”

Things escalated fast that same day … authorities say Moore showed up at Shiver’s home, forced his way inside, grabbed butter knives and scissors and threatened to harm himself.

Moore was facing possible prison time after his arrest … but earlier this month, a judge sentenced him to 18 months’ probation instead.

As we previously reported, TMZ Sports obtained body cam video showing Moore share his side of the story during the arrest. He claimed he didn’t do anything wrong and would never hurt Shiver … but made it seem like his mistress/staffer was out to get him for trying to end their relationship.

He also said if he had fired Shiver or broken things off, she would sue … but he later admitted he was better off going that route.