got some nasty allegations against me online, what do i do?

so i’m gonna keep this short because i’ve had to explain it so many times over the past day or so but anyway.

so went out on a date with this girl and it didn’t go to well, nothing that i thought was that bad but we pretty much agreed to not see each other again, anyway now it’s a week later and one of my friends notified me that there had been some pretty bad things being said about me on a facebook group by an anonymous user.

there’s honestly not any majorly bad accusations but i’ve just been made out to be a total creep, posting things like saying i attempted to sleep with her and that i got violent when i got rejected.

im half asleep typing so feel free to ask for more information,

im just wondering what i should do about this because it doesn’t feel like there’s a lot i can do, its been posted to a very large private facebook group for girls only and they’ve used my full name and photos of me and my social media pages, including bruises on this girls leg that i apparently caused. i’ve got friends that are in this group that are able to report it but um yea im just sort of looking for advise on what to do

LOCATION: Australia Victoria