Kevin Costner Says 'Horizon' Stuntwoman Suing Him Admitted She Lied in Lawsuit

3:33 PM PT -- An attorney for Devyn LaBella tells TMZ ... "It's disturbing to see the defendants continue to 'mansplain' to Devyn what her own experience was on set. She has sworn under oath to the truth and has produced contemporaneous proof to back it up. Ms. LaBella's claims have never wavered or changed since the day she first reported this terrible incident to production in May 2023, right after it occurred."

Kevin Costner's lawyers want the lawsuit alleging he made a stuntwoman participate in an unscripted rape scene dismissed ... because he says the stuntwoman suing him has changed her story ... essentially admitting she lied in the original complaint.

The actor's lawyers filed more legal docs in the case ... and, now they're pointing out Devyn LaBella -- a stuntwoman on "Horizon 2" -- previously claimed she was thrust into the movie's rape sequence without any discussion beforehand.

However, they point out she now admits another individual -- stunt coordinator Wade Allen -- "met with her in advance and explained the shot to her in advance."

Costner's lawyers also say LaBella's admitted before she blocked the shot, she knew the basics of what would happen, including she'd be lying down in the back of a covered wagon and that the actor in the scene would grab her dress and push it up towards her knees.

The lawyers say her claims to the contrary simply don't hold up ... so they want the judge to throw this case out.

Remember ... Costner previously asked for a judge to dismiss this lawsuit -- calling the accusations against him "absolutely false."

Most recently, LaBella claimed she was menstruating on the day the scene was shot ... and claimed her scene partner, Robert Ivens, put his hand on or near her vaginal area and buttocks.

Marty Singer-- Costner's attorney -- has previously called BS on LaBella's claims, as well.