Mel B "taught" her "naive and curious" teenage nanny about sex and became her lover for seven years while she was married to Stephen Belafonte, explosive details contained in new court papers reveal.
According to the Daily Mail, the papers say the ex-Spice Girl would have sex "multiple times in a week" with foreign exchange student Lorraine Gilles, then 18, and enjoyed a "sexual and loving" relationship with her completely separate to her relationship with Belafonte.
The former nanny made the claims in a defamation lawsuit filed during the couple's turbulent divorce battle.
The bombshell revelations come after it was claimed in the suit that Mel plied the nanny with alcohol and had sordid threesomes with her.
Belafonte, who is now estranged from Mel, was not present for "most of the sexual encounters" between the pair and only joined in the sex when invited by the star, the court papers allege.
Mel also allegedly encouraged the nanny, now 26, to make "embarrassing" sex tapes - even though the young woman was "uncomfortable" with the idea.
The striking blond claims that Mel, 41, lied in her divorce papers and wrongly portrayed her as a "homewrecker, jezebel, whore and an exploitative and morally bankrupt individual".
She says allegations that Belafonte fathered a child with her and forced her to have an abortion were lies. And she claims Mel sent her an "ominous threat" in an email to try and dissuade her from taking sides in her divorce.
Gilles said that she met Mel and Belafonte in a Hollywood bar in 2009 after the couple asked her about her "foreign accent" and they later invited her back to their home where they plied her with booze and had group sex.
Although Mel claimed Belafonte hired her to have sex with, Gilles says both of them offered her a job and Mel even offered to have her attorneys work on Gilles' USA visa paperwork so she could move to California from her native Germany.
During her employment, Gilles and Mel regularly had sex and "developed a friendship and sexual relationship with one another that was separate and part from Brown's relationship with her husband," the lawsuit says.
The only sexual relations she had with Belafonte were when Mel would invite him to join in - and she would often record the encounter.
"The only time Gilles and Belafonte had sex was when Brown herself invited her husband to join the couple in the bedroom, at which point Brown would often serve as the 'camera man' and record the sexual encounter or take part in the menage a trois herself."
Gilles also says she has none of the sex tapes in her possession as Mel has previously claimed.
"Gilles was actually uncomfortable with the making of the sex tapes in the first instance and does not want any of the alleged sex tapes to become public, as they are extremely embarrassing to Gilles and the family she loves."
Mel's claims that Gilles became pregnant with Belafonte's child, then paid for her to have an abortion using her money are also false, according to the court papers. Gilles says she became pregnant following a "one night stand" with a man she met at a bar in West Hollywood.
Mel was very "compassionate and supportive" towards Gilles when she told her, encouraging her to make an appointment for an abortion, advancing her the money for it and booking a hotel so she could recover in privacy.
The former singer even took her kids to visit Gilles as she recuperated from the procedure.
"At no point was it suggested or implied that Brown believed Belafonte to be the potential father of the child," the suit reads. "In fact, Gilles had not had group sex with Mel and Belafonte for several months prior to the unexpected pregnancy."
Gilles has blasted Mel for needlessly revealing details of her abortion in her divorce papers and says she now feels "publicly exposed, ashamed, embarrassed and violated by Brown's thoughtless and unnecessary discussion of the abortion in her Declaration".
"The statements made by Brown in her declaration are blatantly and demonstrably false and were made with knowledge of their falsity," the suit states.
The nanny also accuses her former boss of "cruelly and unnecessarily" publicising "highly private and sensitive aspects of Gilles' life."
Dozens of photos and documents attached to the lawsuit show the intimate and loving side of Mel's relationship with her nanny.
In a copy of an email sent in July, 2002, the star gushed about a family visit to Gilles' home town in Germany, demonstrating that her and the nanny had a close bond.
In the email Mel thanked Gilles for "our amazing time in your town", adding: "We had soo [sic] much fun and relaxation i don't think you realize how much we loved it honestly."
It continued: "We all agreed we enjoyed the best staying with you and your amazing family, from you cute pregnant sister to your cheeky dad to your welcoming mum and my fav your grandmum, you don't know how blessed you are."
Mel said it made her sad that she doesn't have that with her own family and describing the time with Gilles' family as "priceless" she said she "cried" when she had to leave.
She added: "From the bottom of my heart i really do appreciate EVERYTHING they have done for us over these past few days, and it felt sooo natural and sweet and comfortable...I sound soppy but family is everything!! xxxx."
In another email exchange in November 2012 Gilles writes to Mel that she can't wait to see her and that she misses her "very much", promising to give her a "big hug".
Mel responded: "Ahhh miss you too we are only in UK for 6 days with no kids and my diary is super slammed."
In recent months Mel sent Gilles an "ominous email" threatening her not to take sides in the divorce.
In the message she wrote that she knows deep down that Gilles is a "good person" and will do the "right thing", adding "but I have to clear my conscience before things get exposed that I did reach out to you as a friend since I have known you and been around you for years."
But she added ominously: "I just don't want you to be forced to choose sides without thinking things through for you own well being and future."
Also included in the defamation suit was a hand-written note to Gilles from Mel sent after she stopped working for the couple, thanking her for everything she had done.
It states: "You sacrificed 7 years of your life and dedicated it to my kids and for that I am more than grateful."
Mel said she invited Gilles to one her children's school as a "special person" as an expression of that gratitude.
She added: "I wish you nothing but always the best in your life and yet again thankyou for everything you have ever done for me and my family and I mean that with a pure heart."
But despite the gushing praise, she ends the note asking her not to contact her and Belafonte again, writing: "Go live your life and have a great time doing it, and please let me live mine with my family, no need to reply to Stephen or I respectfully please!! Mel x."
In other telling sections of the lawsuit intimate photos show how close Gilles and Mel were.
In one photo Gilles and her husband Michael Bleau are seen raising wine glasses with Mel and Belafonte during dinner at a posh restaurant.
This, Gilles claims, is when the two couples celebrated an investment Mel had apparently made to Bleau's company.
In her original filing for a restraining order Mel claimed Belafonte made this investment behind her back.
Gilles is demanding a trial by jury and an undisclosed amount in damages for "humiliation, mental anguish and emotional and physical distress" caused by Mel's alleged "extreme and outrageous conduct".