The 47-year-old TV star discussed details of her alleged fling with the 49-year-old actress, in a teaser for a new episode of 'The Real Housewives of Beverly Hills', saying Denise tried to hide their supposed romance from her husband.
Speaking to Kyle Richards, Dorit Kemsley, Teddi Mellencamp Arroyave, Lisa Rina and Erika Girardi at a sit-down dinner, Brandi says: ''I f***ed her, woke up the next morning [and] she said, 'Aaron [Phypers] can never know this. He'll kill me.'''
The claim prompted a shocked reaction from the cast members.
But when they later confronted Denise about Brandi's accusation, she denied cheating on her husband.
The actress - who has been married to Aaron since 2018 - responds: ''What the f**k? That is not true!''
Later in the clip, the 'Wild Things' actress threatened to quit the reality show if the production team didn't edit the speculation out of the show.
She said: ''Bravo has a choice. If they ever want me to be on the show ... they need to cut that.''
A representative of the TV star has also denied the rumour to PEOPLE magazine.
In April, an insider revealed Brandi had claimed to have had a physical relationship with Denise while she was married to Aaron.
The source explained at the time: ''Brandi says it happened more than once. She says it was never serious, but that they had fun.''
Denise - who has Sam, 16, and Lola, 15, with ex-husband Charlie Sheen, and an adopted eight-year-old daughter, Eloise - was subsequently rumoured to have contemplated quitting the show in order to protect her family.
The insider explained: ''Denise knows this is a reality show, and what she signed up to do.
''But she has three daughters and she's concerned about them - this is about more than the show.''
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