Fiona said speaking to ChildLine was the only time she "felt safe"
The NSPCC has launched an appeal to raise more than £8m to increase its helpline services across Wales.
The campaign, part of the Child's Voice appeal, aims to raise £50m across the UK within the next three years.
Money will be spent on increasing the number of volunteers and counsellors, as well as expanding the NSPCC's text and internet services.
One abuse victim who used the charity's ChildLine service said money was needed because the charity "saved lives".
The service in Wales has bases at Prestatyn and Swansea.
Fiona - not her real name - from Manchester, developed a relationship with a ChildLine counsellor at the charity's Prestatyn centre.
Now 20, she said she was 11 when she began suffering "mostly verbal" abuse at the hands of her mother's partner.
There's children out there that haven't got anyone...if they could just phone up and speak to someone it could save lives
She said: "Speaking to the counsellor at ChildLine, it was like I felt kind of protected.
"It's the only time really that I...felt safe."
She added: "There was a lot of talk about how suicidal I was feeling at the time.
"I'm not saying that I wouldn't necessarily be here if it wasn't for ChildLine but I think I would be a lot worse off now and I would've caused harm to myself, a lot more harm."
Fiona said it was vital that ChildLine and similar services received more money, adding: "I know that ChildLine has saved me and helped me in a lot of ways.
"There's children out there that haven't got anyone and if they just had that someone, if they could just phone up and speak to someone it could save lives.
"And that's literally how important it is - it is life-saving."
ChildLine staff in Prestatyn answered 18,560 calls last year
The NSPCC has secured £30m from the UK government to develop helplines over the next four years, but it says a further £50m is needed.
Organisers hope £8.1m will come from Wales to allow it to allow the expansion of ChildLine bases in Swansea, Prestatyn in Denbighshire, and the NSPCC Cymru/Wales helpline in Bangor, Gwynedd.
Between April 2007 and March 2008, ChildLine answered nearly 29,000 calls at Prestatyn and Swansea.
With additional funding, it hopes to be able to answer at least another 10,000.
It also aims to increase the options for young people wishing to contact them by text or via online services.
Last year, 39% of calls to the NSPCC Cymru/Wales helpline came from adults concerned about the safety of children.
Joanne Leonard, NSPCC fundraising manager, said: "As some children are unable to speak out for themselves - particularly younger children - we want to expand the NSPCC helpline so that there is greater capacity to answer calls from adults with concerns about a child."
Wales rugby captain Ryan Jones, who supports NSPCC Cymru/Wales, said: "Every time a caller doesn't speak to a counsellor, a child's safety may be at risk.
"You can make sure more calls are answered by supporting the Child's Voice Appeal."