Zac Stacy told cops the brutal attack on his ex was all "staged" ... claiming the woman set him up because she was "bitter" he didn't want to be with her.
The former NFL running back's conversation with officers was all captured on police video, obtained by TMZ Sports, just days after he ruthlessly beat his ex at her Florida home.
In the arrest footage, Stacy can be heard speaking with Orlando Police Dept. officers for several minutes about the events that led up to the Nov. 13 altercation ... insisting it all "was staged.