Some called it a "blatant attack on morality", others an "evil" scheme "using wealth to promote vice". In one dark corner of the internet, Melinda Gates found herself accused of promoting Nazi-style eugenics in a shameless attempt to "make sure that there are fewer Africans".
It's not easy being rich. Not when you're arguably the richest woman in the world, with a husband whose fortune is estimated at $53bn (£34bn); and certainly not when you decide to pursue a charitable endeavour that upsets religious institutions and offends the forces of conservatism.
Ms Gates spent her week doing just that, though, when she swept into London, with a suitcase full of trouser suits, and announced that her charitable foundation would be giving $560m (£375m) to a campaign to provide contraception to women across the developing world.
The gift, part of a $4.3bn effort led by the British Government, would "give a voice" to 120 million women who have little or no access to family planning, Ms Gates said, and reduce an estimated toll of 9,000 women and children who die each day because of unwanted pregnancies.
At the age of 47, she intends to devote the rest of her life to widening access to birth control. "This," she told an interviewer, "will be my life's work."
The move, unveiled in Westminster before an audience that included David Cameron, cements the status of Melinda Gates as the pre-eminent philanthropist of our time; perhaps of all time. Married to Bill, the founder of Microsoft, she represents what you might call the acceptable face of the one per cent: a socially responsible version of the old Hollywood anti-hero Montgomery Brewster.
It also leaves Ms Gates, who has pledged to give away at least 90 per cent of her net worth during her lifetime, in the firing line. A serious, shy woman, who uttered nary a word in public for the first 14 years of her marriage, her decision to make sexual health her signature issue has thrown her to the centre of America's rambunctious culture wars.
At issue is a matter of faith. Ms Gates was raised a Catholic. She has introduced her three children to the faith (although Bill is resistant), and remains a regular churchgoer. Yet her endorsement of contraception puts her directly at odds with both the Vatican and America's Catholic leaders, who are particularly vociferous on sexual morality, despite their own recent failings on that front.
In May, for example, her church waded into Tea Party politics to vigorously oppose an effort by the Obama administration to ensure that health insurers covered contraception. In 2002, it joined the religious right in persuading George W Bush to withdraw funding for the UN Population Fund.
Conspiracy theorists, of whom there is no shortage on the extremes of US politics, are now citing Ms Gates's previous attendance at Bilderberg conferences and friendship with Democratic tycoon Warren Buffet as evidence of sinister left-wingery. The anti-abortion website lifesitenews.com yesterday accused her of attempting "to give brown women Depo-provera".
If Ms Gates was thinking twice about poking this hornet's nest, she wasn't showing it this week, however, as she took to the airwaves to endorse her cause, sounding intelligent and well-briefed as she threw out statistics and geopolitical analysis alongside heart-rending anecdotes concerning women she's met on various tours of the Third World.
"Of course, I wrestled with this," she said. "As a Catholic, I believe in this religion. There are amazing things about this religion, amazing moral teachings that I do believe in, but I also have to think about how we keep women alive. I believe in not letting women die, I believe in not letting babies die, and, to me, that's more important than arguing about... contraception."
It was a virtuoso performance, marking a sort of transformation. Once the opaque life partner of America's wealthiest geek, Ms Gates has morphed into a dynamic public figure, on first-name terms with world leaders and rock-star humanitarians.
"Melinda really walks the walk," says a colleague. "In fact, she came to the summit straight from Niger and Senegal. She's in Africa three or four times a year, often in pretty sketchy places. So when you hear her speak about issues, you really feel her emotion and passion. She's a genuinely talented advocate."
Bono, a long-time friend, once summed up Ms Gates's charms by declaring her: "Fun to hang out with, and funny." The $125m pile on the shores of Lake Washington where she and Bill raise their children – Jennifer, 16, Rory, 13, and Phoebe, 10 – has a sense of "Zen" to it, he declared, admiringly. "Melinda has created that."
Life wasn't always so glamorous. Born in 1964, and raised in a middle-class suburb of Dallas, she became a hard-working young woman who took a BA in computer science and business at Duke University, followed by an MBA.
Her relationship with Bill was initially an office romance, which began shortly after she joined Microsoft, straight out of university, in 1987. They first met at a company dinner, in New York, and began dating after a chance meeting in a car park four months later. He was a newly minted billionaire in charge of America's hottest tech firm; she was a lowly new recruit to the marketing department.
It was hardly a whirlwind. In fact, things stayed off-and-on for years, as Bill devoted his energies to world domination. Their partnership was so discrete that when tech writer Stephen Manes published a biography of Gates, in 1993, she was referred to only in passing.
That changed soon afterwards, when Bill's mother Mary, a Seattle socialite, fell terminally ill. Rapidly approaching his 40th birthday, the Microsoft founder decided to settle down. They married on New Year's Day in 1994, six months before Mary's death.
Melinda promptly left Microsoft to start a family and began exploring her husband's long-neglected philanthropic interests.
"The place she occupied in his life was almost as a replacement for his mother," says Marc Aronson, author of a recent biography of Gates. "Mary had been very involved in philanthropy. Bill had been a somewhat rapacious builder of a company. As he came to the age when he wanted to settle down, he found a woman similar to her."
The Bill & Melinda Gates Foundation came into being soon afterwards, and has since distributed about $26bn in fields as diverse as Malaria prevention and education. It's run from a vast, boomerang-shaped HQ in central Seattle, where the couple share space-age offices connected by an interlocking door (Bill these days devotes only a fraction of his work life to Microsoft).
For the first 14 years of the Foundation's existence, Melinda took a behind-the-scenes role. "When the kids were very young, she felt it gave them more privacy," says a friend. But in 2008, once they had started school, she emerged from the woodwork, giving a series of interviews to launch her career as a public advocate.
It hasn't exactly been plain sailing ever since. Some have criticised the investment strategy of her Trust, which finances the Foundation, and has money in oil firms with contentious footprints in Africa, along with controversial "frankenfood" giant Monsanto. Others wonder if the sheer size of the Foundation, which employs almost 1,000 staff, makes it a sort of Microsoft of the non-profit world: a clunky institution with unhealthy dominance in its chosen fields.
Occasional commentators have meanwhile raised eyebrows at Ms Gates's occasional habit of talking about wealth as, in the words of one recent interviewer, "a cross she must bear".
Yet watch Melinda Gates in full flow, and it's hard to stay cynical for long. "At a time when many of the world's richest people seem to think lower classes are prey placed on Earth for their benefit, it's uplifting to see someone dedicate their life to the betterment of others," says Dick Brass, a former colleague. "In 100 years, the technology accomplishments and success of Microsoft are unlikely to be remembered. But the tens of millions of lives Bill and Melinda are saving will be remembered forever."
A Life In Brief
Born: Melinda French, 15 August 1964, Dallas, Texas.
Family: Married Bill Gates in 1994. They have three children: Jennifer, Rory and Phoebe.
Education: Ursuline Academy, Dallas; Duke University (BA in Computer Science and an MBA).
Career: Went to work for Microsoft in 1987, developing multimedia products. After marrying Bill Gates in 1994, she left the company and became the co-founder and co-chair of the Bill & Melinda Gates Foundation.
She says: "The premise of this foundation is that one life on this planet is no more valuable than the next."
They say: "We're proud of Melinda French Gates, her dedication to social justice, her compassion for the underserved." The nuns of the Ursuline Academy of Dallas.