A woman going by the name of Jacklyn Knight had pictures of Seguin on her own Facebook profile as if they were pictures of herself.
There were photos of Seguin with her friends, photos of Seguin participating in a bikini competition.
Seguin, a 22-year-old Montreal barmaid, was floored.
The good Samaritan, Brittaney, told Seguin that Knight had hundreds of pictures of her on her profile and that the page had been in operation for about four years.
She also told Seguin that she believed "Jacklyn Knight" was a pseudonym.
Because of limited privacy settings, Seguin could only see a few photos — but what she saw was enough to send her into a panic.
Brittaney had scoured the Internet for two years looking for Seguin, and she finally found her three days ago.
She believes the woman, who calls herself Jacklyn Knight, to be her fiancé's former girlfriend, whom CBC News cannot name for legal reasons.
Brittaney alerted Seguin that her photos had been compromised. She also told Seguin that Knight had been messaging her and her fiancé, encouraging him to get back together with his ex-girlfriend.
However, the Tennessee woman has not yet been able to prove Knight's true identity, despite strong suspicions.
Through online searches, Seguin now believes she is a victim of catfishing, defined by Urban Dictionary as Internet predators fabricating online identities to pursue relationships with other people.
Seguin reported the breach to Facebook, but she says the popular website didn't even acknowledge receipt of her complaint.
She says her next step is to take her complaint to both the Montreal and Tennessee police — and tightening her Facebook privacy settings.
Listen to Daybreak's interview with Seguin: