An insider claims that Horner hasn't responded to messages from Mel B ever since she confessed during an interview with Piers Morgan that the two women slept together, and it's causing drama among the rest of the Spice Girls — who are embarking on a reunion world tour later this year.
That may be because Mel B and Horner's relationship extended beyond a one-night stand.
Insiders told The Daily Mail that Horner and openly bisexual Mel B were actually in a romantic relationship for a year.
"It was in the very early days of the Spice Girls and their relationship lasted far longer than one night – it was at least 12 months. They deeply bought into the whole Girl Power phenomenon — they wanted to lead it," the source said. "They felt what better way was there to do that than for girls to enjoy one another?"
Horner and Mel B reportedly fell in "lust at first sight" when they first met at ages 21 and 18, respectively.
Horner has been married to Christian Horner since 2015.
She previously said of her sexual experiences with other women, "I don’t mind boobs but the other bit is not my cup of tea. I realised I was not a lesbian. It is part of experimenting."
Meanwhile, Melanie "Sporty Spice" Chisholm (Mel C) was in the audience during the interview and reportedly mortified at the revelation.
“The girls are due to start rehearsals next month, but the whole thing is in chaos. She’s not replied to any of her messages and is properly sulking," a source told The Sun. “Mel C is unhappy too as she felt put on the spot, and publicly humiliated. She simply doesn’t want the drama of it all.”
In the same interview, Mel B reportedly called Victoria "Posh Spice" Beckham a "b—h," further irking the rest of the Spice Girls.
“Victoria doesn’t want anything to do with this reunion malarkey," the source said. "It’s exactly this sort of nonsense she wanted no part of."
The Spice Girls reunion tour kicks off on May 24 in Dublin, Ireland.