The woman said when her cousin quickly called her to notify her of the news she thought it was a joke, news.com.au reported.
"It was so unbelievable for me," she said, however she asked her cousin to take screenshots for evidence.
She then impulsively phoned her aunt to confront her, saying "she had the audacity to immediately delete the entire thing as they were talking, while obviously explaining that is was just a joke".
Writing on Reddit, the woman said: "We decided to give my aunt a week to confess (which she's not going to do) and then we will show the copies first to my uncle and then my mum."
She then asked commenters to weigh in on the situation, asking whether she is doing the right thing, and whether she should just tell her mum now.
"Your mum absolutely needs to know, do NOT fall for the age old 'I need to hide this to protect her' fallacy," one person wrote, adding, "It will hurt her, but she deserves the truth."
The same commenter said they thought it was a "huge mistake to give it a week".
"You've said yourself she's never gonna confess it, so all you're doing is giving your dad and your aunt time to go to ground and map a strategy, maybe clean up the bank accounts and God knows what else," the person said.
"You should have told her immediately, before they have time to strategise and mount a counter offensive."
However, others believed it wasn't a good idea, saying there were consequences.
"There are ramifications here that need to be explored. Your cousins, for instances, might be your half siblings," they posted.
The woman took all the comments on-board adding, "It's still hard for me to come to terms with all of this."
