"I just had this chilling, weird sense of the contents," said the Queen's University professor who lives in the city with her partner Susan Belyea, 48, and their 13-year-old son.
The letter claimed to be authored by a "small but dedicated group of Kingston residents devoted to removing the scourge of homosexuality in our city."
"I won't say that we're not afraid," said Dubinsky, 55, adding that she and her partner of 21 years had the same response.
"We weren't going to take them up on their offer and leave town."
The letter threatened violence if the family did not leave.
"We will watch and wait, and then strike, at home and office, as need arises," the letter read.
It was followed by a second note that threatened attacks using BB guns if the couple didn't relocate.
Both letters were circulated on Facebook by the couple and their supporters.
Dubinsky said she immediately reported the letters to the police.
Spokesman Const. Steve Koopman said the police are taking the threats "very seriously" and that the "hate-based" letters were "a shock" to the entire community.
He said the letters could originate from anywhere and detectives from the major crime unit are following every lead.
One of the letters contained claims of ties to Kingston police.
"We absolutely, unequivocally believe that not to be true," Koopman said, adding that he believes it was included as an "intimidation factor."
He said the author or authors of the letters could be charged with criminal harassment and uttering threats to cause bodily harm or death.
Since receiving the letters, Dubinsky said her family and friends have taken to sitting on the front porch to "be visible."
In almost 20 years of living in Kingston, Dubinsky said she's never been on the receiving end of homophobia, even in a "milder form."
The couple's son is a "savvy kid" who "takes things like this in stride," Dubinsky said.
"Having said that, he's a kid and people just threatened his family," she said. "The violence stuff is scary for him as it is for all of us."
Dubinsky said the letters leave a lot of questions unanswered and she doesn't know if anything will come of the investigation.
She added that her family is grateful for the community response, which has included flowers delivered to her doorstep, phone calls and support rallies.
"That helps us meet this kind of hatefulness," she said. "It makes it easy to find courage."
_ By Clare Clancy in Toronto.