Why doesn't she want his child there?
She later added more information to the post, as she explained her reasoning behind not wanting the child at the wedding.
"Edit cause people keep asking me the same dumb a** questions," she added. "She's three. I am marrying him not his crotch goblin. That's his mistake not mine.
"I don't want her there because she's needy asf and makes everything about her AND I said no f***ing kids!
"If you don't have [anything] nice to say or any advice then SCROLL ON!" she added.
Since she shared the post in the Facebook group, it has garnered over 1000 comments from different users.
Most users have revealed their shock at how the woman spoke about the young child.
One user said: "I'm pretty childfree and I think this is absolutely abhorrent.
"If you don't want to be in a partners kid's life, don't be with that person at all! When I was single I had a strict no dating parents policy for this reason (sic)," she added.
Another user commented on the post, saying: "She's 3... of COURSE she makes everything about her ... that's all she knows.
"This marriage (if it happens) is gonna end quick or last way to long and be horrible the entire time (sic)," she added.
Another user couldn't believe the post was real, as they said: "Omg pls let this not be for real!! How does she talk about her fiances kid like that?? Omg this makes me want to cry."
Similarly, another said the post made her feel sad. "Nope this just makes me so so sad, how old is this woman?"
The woman's post was later re-shared on Reddit, where it has also garnered a lot of attention.
Should she be marrying someone with kids?
One user on the online forum said the woman shouldn't be with someone who has a child if she doesn't like children.
"Why marry someone with kids if you don't like kids?" they said. "There are plenty of single, childless people out there. We don't all have children," they added.
A different user said: "Lady, when you marry a man, you marry his family. The fact that your refer to his daughter as a 'crotch goblin' is a major red flag an he needs to dump your sorry a**."
Several other users pointed out that the woman's attitude to the three-year-old was concerning, as they referred to it as a "red flag".
One user said: "No red flag exist that is bigger and brighter than this one," while another added: "I think the bigger red flag (redder flag?) is that she calls his 3yo 'his mistake'."
Another person branded the woman a "terrible human being". The user wrote: "There is a really good reason no one has anything nice to say because you are a terrible human being.
"Also, if him having a child was going to that much a problem why still be in the relationship?
"He's still going to raise and love his daughter so either you grow up and be a stepmother as that's what comes with the marriage or break it off if you can't commit.
"Also one last thing, she's three you dumba**, she's still practically a toddler (almost child)", the user added.
Calls to cancel the wedding
A different user simply stated: "The groom needs to cancel the wedding ASAP."
Similarly, another Reddit user stated that the groom "needs to get rid of her real quick".
Another said they thought the woman would be the "worst stepmother ever" if she married the groom and became stepmother to his child.