The 37-year-old singer had reported the woman to the police and to her children's school, after fearing she would try and take them.
X Factor winner Sam told the Mirror: "I posted a photo of me in a nightclub when I was pregnant with Miley, pulling a silly face with mates.
"She took that as I was absolutely steaming drunk. I don't actually drink but suddenly she hashtagged me on Twitter, and was writing loads of things like I was harming my baby and emotionally abusing my children.
"The hashtag meant that anytime someone typed in 'Sam Bailey', this would come up."
The woman's 'complaint' led to sam being investigated by social services, forcing Sam to defend herself.
She continued: "Next thing I know, she had reported me to Social Services. I actually got a call from them, asking me about emotionally harming my children. The school had to get involved. It was awful.
"I had to contact the police, my solicitor and my management, and screenshot every conversation we ever had."
Sam, who has Brooke, 9, Tommy, 5, and six-week-old daughter Miley with husband Craig, 41, was convinced the 'stalker' would try to take her children.
"I had to take a photo of the woman into the school because I was concerned she would go there and pick my kids up. I was petrified," she said.
Thankfully for Sam, Social Services had no concerns over her children and the woman has since been contacted by the police.
Sam added: "I'm not sure what happened, but she disappeared. I don't think she'll be doing it again."