Divorcee Elizabeth Scarlett had former pupils aged 11-17 as friends on the site, and posted about getting drunk and having sex.
One post read: “Getting pissed, dancing and pulling a big black man.”
Another referred to a sex toy, saying: “Thinking of buying a rampant rabbit.”
A message to an ex-pupil read: “You should pop up to see me or even better we can go out for a drink or clubbing. I’m a very different person outside school. I like to party hard – life is for the living. I’m not a teacher on here. I’m just like anyone else. I drink, swear and shag. But don’t tell anyone.”
Headteacher Graham Phillips told the Genearal Teaching Council for Wales hearing in Cardiff: “I was shocked by what I saw on Facebook. I thought it was inappropriate and improper.
“When you become a teacher I think you agree to uphold a certain set of standards to behave in a certain way and act as a role model.
“But you grossly overstep the line when you post about drinking, swearing and details of your sex life.”
Scarlett has taught at Trinant Primary in Crumlin, near Pontypool in South Wales, since 1993, but left due to illness.
She claimed to have taught over 500 students and worked in Africa on an exchange trip to Lesotho.
In a statement, she said she “did not realise” the messages she wrote three years ago could be seen publicly.
She said an ex-partner hacked into her account and wrote the sexual comments on her profile.
The Council said it was satisfied that Scarlett hadn’t sent the public messages but disciplined her with an official reprimand, which will stay on her record for two years.