Phil Collins' Ex Says He Promised Half of Mansion, Claims Bad Hygiene

Phil Collins' ex says he's going back on his word to give her 50-50 ownership of the home he's now trying to evict her from, and she's saying he became a filthy mess along the way.

Orianne Cevey filed new docs in the ongoing legal battle between her and her famous musician ex-hubby -- who's trying to boot her from their Florida mansion. In her response, obtained by TMZ, Orianne claims Phil made a deal with her that she says he's now trying to back out on.

Basically, Orianne says that in 2015 ... she and Phil rekindled their relationship, and she claims Phil told her that if she divorced her then-husband, Charles Alami, and relinquished her stake in their $20 million estate on Sunset Island in Miami ... he'd give her a 50% stake in their new pad.

Orianne says she agreed and did exactly that -- even moving back in with Phil and their kids and snapping up a massive property in Miami Beach that she says she made her own over the past 5 years.

After a while though, Orianne says things went south ... as she claims Phil became a hermit and completely secluded himself from the world. She also says he lost his musical talents and began abusing pain killers -- and adding insult to injury ... she says he stank.

Orianne mentions a very detailed state of squalor she says Phil allowed himself to fall into -- claiming he stopped brushing his teeth and refused to shower for damn near a year, from 2019 to 2020. Orianne says his stench became unbearable and that by 2019, he was incapable of having sex. She claims "Philips stench became so pervasive that he became a hermit, refusing to interact personally with any people."

As to the meat of the issue -- Orianne is sticking to her story, that Phil promised her half of the home, and is now trying to jettison her without honoring the deal.

The stench of relationships ... it's in the air tonight.