Brian Edwards and Tom Privitere, a New Jersey couple married in 2010, were horrified when a photo of them kissing at their engagement party was altered and turned up in an anti-gay unions mailer 2,000 miles away.
The playful photo had been posted on Edwards' personal blog and was originally set against the backdrop of the New York City skyline.
But the doctored photo showed the gay couple standing in a snowy Colorado setting and was used in a political campaign to attack a Republican who supported civil union legislation.
The tagline for the ad, which was sponsored by Public Advocate of the United States, was: "State Sen. Jean White's Idea of 'Family Values?'" White later lost the primary.
Now, with the help of the Southern Poverty Law Center (SPLC), the couple and photographer Kristina Hill are threatening to sue the organization behind the ad and its president, Eugene Delgaudio, if they do not stop using the photo.
"Our initial reaction was complete shock," said Privitere, 37, who works in entertainment ticketing and lives with Edwards in Montclair, N.J. The couple has been together for 12 years.
"We were heartbroken to see that our picture that was taken to represent love and family, and our values, and to share with other LGBT couples, was used for complete opposite purposes to induce fear and spread hate and bigotry," he said.
Public Advocate, based in Falls Church, Va., is on the SPLC's 2011 hate group list. It never had permission to use the photo, according to Hill, who runs her own wedding photography business.
Delgaudio, who is head of the board of supervisors for Loudon County in Virginia, told ABCNews.com that he has not yet received SPLC's letter and is "looking into the matter."
"I am searching whether or not we have the photo," he said. "I have not commented on this ever and I have no statements on it. ... Someone could do this without my permission -- but I am working on it."
Public Advocate, a grassroots advocacy organization, claimed that "thousands flock" to its website and called the Southern Poverty Law Center a "prehistoric dinosaur."
"I have no idea what that means," SPLC lawyer Christine Sun told ABCNews.com.
She said Public Advocate has 10 days to respond to her letter and then SPLC will make legal copyright claims for Hill and state law privacy claims and infliction of emotion distress on behalf of Edwards and Tom Privitere.
"Beyond a lawsuit ... we decided to get involved because these actions are truly reprehensible -- to take a personal photo of the happiest day in a couple's life and use it in a homophobic attack ad," said Sun. "It's demonizing, unfair and unjustifiable."
The couple learned the photo had been taken without authorization from a friend who saw it in a mailer from Sen. White and called them in June.
"Our immediate reaction was to find out where it had come from," said Edwards, 32, a college administrator. "We scoured the Internet and found an article in the Denver Post to find out more."
"We went through the whole process of anger and heartbreak," said Privitere. "And now that we are on this road, we are trying to get some justice not just for us, but for other couples."
Christian Advocates Not Listed as Hate Groups
SPLC's criteria for listing hate groups is based on those who "demonize" a class of people with "misinformation and lies," according to Heidi Beirich, director of the SPLC Intelligence Project. Such groups include the Ku Klux Klan, anti-Semitic organizations, neo-Nazis and black supremacy groups.
"There are only a handful of anti-gay groups," said Beirich. "We don't list those who are against gay marriage or the Biblical prescription against gay marriage -- only the groups that are engaged in demonizing propaganda and lies about the gay community and basically lying about them to make them pariahs."
Previous campaigns by Public Advocate include:
A fundraising letter asking recipients to "imagine a world where police allow homosexual adults to rape young boys on the streets?"
Comparing same-sex marriage to bestiality.
Suggesting having gays as Boy Scout leaders is "the same as being an accessory to the rape of hundreds of boys."
Characterizing campaigns to stop anti-LGBT bullying as "requir[ing] schools to teach appalling homosexual acts ... force private and even religious schools to teach a pro-homosexual agenda."
"I use colorful language and hyperbole, but when I say something like, 'Keep Obama away from your children,' I am not stupid, I know it's hyperbole," said Delgaudio.
"We definitely have 2,000 photos and in the neighborhood of 80 to 100 videos on my website, and if someone doesn't want us to use it, we take it off," he said. "We seek permission or we take the stuff off that's not in the public domain.
"This may be the first objection in 30 years," Delgaudio said. "Frankly, we are not distributing this photo and I'd be hard pressed to find anything today. Mostly, this an attack on me from previous statements I've made."
As SPLC waits for or a response from Public Advocate before the threatened legal action, Edwards and Privitere hope the incident is a teachable moment.
"We want to use this as an opportunity to educate people and show them that a gay couple can and do have loving relationships," said Edwards.
"This sort of thing has a trickle-down effect," said Privitere. "I think of all the closeted gay high school students who got mail that day and felt disheartened that they would never have a family and the parents on the fence about whether to accept their gay child for who they are. That hurts.
"These people are spreading lies, and I want them [recipients of the mailers] to know they have our support," he added.