His is one of the latest cases of homophobia in France, where activists say reports of verbal and physical assaults on gays have surged amid rabid debate over a bill allowing same-sex marriage, currently being discussed in the Senate.
"Sorry to show you this. It's the face of homophobia," de Bruijn, a Dutch man living in France for 10 years, wrote on his Facebook page next to a photo of his battered face that has been shared thousands of times.
Elizabeth Ronzier, head of SOS homophobie, said there had been a 30% rise in reports of homophobic and transphobic assaults last year compared to 2011, with a marked surge when debate began in the autumn.
"And in the two months to the end of February this year, we received the same amount of testimonies that we would normally get over a period of six months," she said.
The bill has galvanised public opinion in France, not only on the streets where supporters and opponents have regularly faced off in nationwide protests attracting hundreds of thousands, but also among friends and family.
Despite this, it has made its way through the legislative process, adopted by the cabinet in November and the parliament's lower house in February. It is now in the Senate, where debate on the bill is due to end Thursday or Friday.
More homophobes 'expressing themselves'
"It's difficult to say whether there are more homophobes than before, but there are more who are expressing themselves," said Nicolas Gougain, spokesperson for the Inter-LGBT, a rights group for lesbians, gays, bi and trans-sexuals.
Protests have been led mainly by religious groups and conservatives in a country that is officially secular but predominantly Catholic.
They have focused not only on same-sex marriage, but also on other aspects of the bill such as allowing gay couples to adopt children.
And while polls in France regularly show that a majority of people support gay marriage, far less are in favour of same-sex adoption.
Some of the demonstrations have turned violent. Last month, police were forced to fire tear gas on people protesting the bill in Paris, and dozens were arrested.
Opponents insist they are not against homosexuals, but that marriage is an institution meant for a man and a woman, pointing to civil unions that already exist for same-sex couples.
Heckling by far-right militants
But as the bill progresses towards final approval - or less likely, rejection - some opponents have upped the ante, resorting to more radical actions to get their message across.
Senator Esther Benbassa, for instance, says her car was trashed over the weekend - a move she believes is linked to her support for the bill -and that she has received threatening phone calls, emails and letters for days.
Erwann Binet, a Socialist MP who supports the bill, has also been forced to cancel planned debates for security reasons after being heckled by far-right militants, who have taken a front seat in the debate.
The main opposition movement "Manif pour tous" has sought to distance itself from these actions, saying they are the work of a radical few. But activists say that's not enough.
"Men and women in the Roman Catholic church, in the (right-wing) UMP party... must realise that to say all the time that homos are dangerous for kids, to place them in sub-categories, is... an extremely hurtful form of discrimination," de Bruijn said on Wednesday on France Inter radio.
"It's the tone that makes me fear that many other less educated, less polite people let loose."
And the sheer scale of opposition in a country governed by the motto "freedom, equality, fraternity" has surprised more than one.
But experts have sought to calm fears, pointing to mass protests and opposition in the late 1990s surrounding adoption of France's PACS - a form of civil union between two adults of different or same sex.
This was a bill "that was adopted with a lot of difficulty, with huge opposition on the streets - as big as today - with a third of French mothers who opposed it, debates that lasted hundreds of hours," said Frederic Martel, author of the book "Global Gay".
"The law was finally voted on at the end of 1999, and a year later, it was unanimously accepted in the country... That allows us to put into perspective the opposition to this bill."