Olivia Wilde and Jason Sudeikis' ex-nanny isn't backing down from her toxic claims, despite the estranged couple teaming up to call her a liar ... spilling another bunch of alleged details from their past relationship.
The nanny, who we're told is a woman named Erika Genaro, tells the DailyMail Olivia was stringing Jason along even following their split ... continuing to sleep in the same bed and sending him loving texts from time to time.
Genaro also claims she got a text directly from Jason calling Olivia a "deeply hurting mess" who wasn't living in reality.
The nanny says Olivia even gave her dog, Gordon, away within weeks of meeting Harry Styles -- allegedly so she could have more free time to spend with the singer.
As we reported, Olivia and Jason put on a united front against their former nanny Monday ... telling TMZ her claims are "false and scurrilous accusations" -- referring to her words as a year-and-a-half campaign of harassing them.