EXCLUSIVE

Stephanie Hayden is now claiming she too was sexually abused as a child by her father, Will Hayden ... and will be providing information to law enforcement to aid in the prosecution of her dad ... TMZ has learned.

Stephanie -- who appeared on the Discovery reality show "Sons of Guns" with her father -- originally came to Will's defense last month after he got arrested for the alleged sexual abuse of his 12-year-old daughter.

We're told Stephanie is now recanting her original statement -- and plans on meeting with investigators in Baton Rouge as early as next week to provide specific details of the sexual abuse she allegedly suffered.

Kris Ford, Stephanie's husband ... recently posted a poem on Facebook that appears to be directed at Will: "You fooled with my wife when she was young. Sucking and groping, do you remember what was done?"

Stephanie went on FB to respond to Kris' poem ... telling a relative she gave her husband permission to post it. Both posts were eventually taken down.