Rosa Esperanza Reyes, 17, showed up at a church to stop her 40-year-old lover from marrying his fiancee.
She was carrying their one-year-old child and claimed to be pregnant again.
But despite the fuss, two-timing Jose Sabino Davila still married 18-year-old Rita Elena Lopez at the church in Masaya, Nicaragua.
And authorities are now urging the young woman to report her boyfriend, as she is under the legal age for consent in the country.
Holding her baby, she told authorities Davila was the father of the child in her arms and the unborn one inside her, and that he had even stayed with her the night before the wedding.
She said: "I am his wife, I have his son and I am pregnant. I am only 17 years old. I am here to stop the wedding, do you know why?
"Because I am pregnant and I want to avoid the wedding so that neither I nor the bride will be with this man."
According to local media, Rosa Esperanza has had a relationship with Davila for thre Edwin Roman, the priest who married the couple, said: "Apparently, the bride already knew that her boyfriend had another girlfriend so she was not surprised over the scandal outside the church."
The incident has caused outrage in Nicaragua, where the age of sexual consent is 18.
Lawyer Manuel de Jesus Chavez said Davila could face two to four years in prison if found guilty of sex with a minor aged 14 to 18.
Prosecutors say they are waiting for Rosa Esperanza to report the case officially so that they can charge the groom.
Elia Palacios, president of Women Against Violence, said: "This is a crime. It has to be seen as a crime and the first thing we should do is to find the man, arrest him and judge him for the crime of raping a minor."