The Portadown woman decided to speak out, at the request of her daughter, after the man was sentenced last Thursday to three years in prison.
The abuse and subsequent court proceedings took place over a period of two years, during which time the teenager, now almost 16, resorted to self-harming and took an overdose.
Due to reporting restrictions, neither the defendant nor his victim can be named to protect the identity of the girl.
Speaking to the Portadown Times this week, the mother said her daughter was just 13 when the abuse began in June 2006 and that it continued for seven months.
She said, "During that whole period of time, my daughter was quite moody and withdrawn but I put it down to her being a teenager. Then, one day in February I found a page which had fallen out of her diary, and it mentioned a BEBO page where people were asking if she was pregnant by this man.
"That disturbed me, to put it mildly. I knew something was wrong. When she came in from school, I talked to her for three hours, and it took all that time for her to finally admit to me what was going on."
The mother added, "It turned out he used to meet her at all hours, when I thought she was in bed. He used to drive her to a lane and at other times he would sneak her into his own house or into his sister's house.
"By that stage she was totally infatuated with him because of what he was filling her head with. She thought they were having a proper relationship. He was telling her he loved her and that he would be there for her - as long as she didn't tell anybody about what was going on."
The teenager's mother contacted the police as soon as her daughter admitted what had been taking place. Just a few weeks later, another teenage girl also came forward with further allegations, and the man was arrested in May 2007.
The mother said, "At first, he denied having any contact with my daughter but when the records of his phone calls came in, it showed he had been phoning her frequently and at all hours of the morning.
"My daughter was also able to give a fantastic description of his whole house, right down to the colours of the duvet covers, and of his sister's house as well.
"There were also other intimate details relating to him that my daughter was able to describe in detail."
She added, "He had known our family and my daughter since she was three and he knew exactly what age she was when everything was taking place. At the beginning my daughter didn't want us to go to the police or to take it to court but we knew we had to. If we hadn't, he would have been free to target someone else, maybe an even younger girl.
"It took four or five months for it to sink into her head that he didn't really love her, but that he was simply a pervert who had groomed her to get what he wanted.
"That's when the self-disgust set in and earlier this year she took an overdose and spent three days in hospital. That was rock-bottom for her. We also found out she had been cutting herself, and had been hiding it from us."
hours
The trial took place in June, and lasted for two weeks, with the teenager giving her evidence via video-link, during which time she was cross-examined for four hours.
A jury found him guilty on five charges, three of unlawful carnal knowledge of the girl, and another two charges of unlawful carnal knowledge of a 17-year-old girl.
He was cleared of three other charges - one of kidnapping and two of rape.
Last Thursday, the defendant appeared at the Crown Court sitting at Craigavon Courthouse where he was sentenced to three years in prison. He was also ordered to be placed on the Sex Offenders' Register for an indefinite period.
The defendant has been in prison since his arrest and has already served 16 months.
"We have been told he could be out in two months' time," said the girl's mother. "My daughter could bump into him walking down the main street in Portadown. Any of us could. I would urge parents of young girls to be very careful."
The mother said her daughter is now "doing really well" and will be sitting her GCSEs this year.
hard
"The past two years have been very hard and she has had to grow up very quickly," she said. "I would just like to thank the staff from the Care Unit of the PSNI. They were fantastic with my daughter, and with me and my husband.
"Now the trial is over, we want to make a fresh start and let our daughter get on with her life."