KATE is 16, gorgeous, clever and funny as hell - she's also had unprotected sex with at least eight different boys, which is not so clever or funny.
This girl is friends with my daughter and I've come to know her because they have spent many hours together at our house.
She's one of those lucky people who gets top marks without studying, excels at sport and is at the centre of a huge circle of friends. So finding out that this girl who seems to have so much going for her is so promiscuous has shocked me.
My daughter betrayed her friend's secret to me because she is scared for her. Miss 16 tells me she has talked to Kate about using condoms and urged her to talk to her mum about going on the contraceptive pill but so far Kate has failed to follow this advice.
In fact Kate has told my daughter she doesn't need to do any of that because she doesn't think she can get pregnant.
Seriously, this is what she told my daughter - how can someone who gets an A for English, Maths and Science be that stupid?
So now I'm left wondering what to do?
I've picked up the phone a couple of times determined to talk to Kate's mum. I always tend to think honesty is the best policy, especially if it is delivered with genuine care and concern but in this case I'm torn so I hang up before the call connects.
I know the mum because of our daughters being mates but I wouldn't say we were "friends".
And if I say anything it will be obvious where the information came from and that puts my daughter's friendship with Kate and everyone else in their circle of friends at risk.
And then there's the fact that my teenager has told me these facts in confidence so if I speak up I am damaging that bond of trust between us as well. Then I wonder if she's told me so that I DO interfere and say something.
If it was my daughter who was being so irresponsible, I would most certainly want to know. What bothers me is that I'm not sure everyone feels the same way.
Kate's mum knows her daughter drinks to excess, she knows Kate likes the "bad boys" and that there is always a different boy hanging around her girl, so why hasn't she made sure her daughter is protected from any mistakes she might make. If she can't see what's going on, will she appreciate finding out from me?
I've thought about talking to Kate myself, but then again I would be betraying my daughter's trust in me. And if she won't listen to my daughter why would she listen to me?
But what if she's wrong and she does end up pregnant? Would I wish that I had spoken up and maybe saved this girl from having to deal with the repercussions of whatever decisions that results in?
Not that pregnancy is the worst-case scenario here - some of the sexually transmitted diseases she's exposing herself to could have an even greater impact on her life than a baby or abortion would.
Or is it none of my business?
People are fond of trotting out that line about it taking "a village to raise a child", but I'm pretty sure that there are just as many who would tell me I shouldn't be "sticking my nose into other people's business".
How would you handle this tricky situation?
* Life with teenagers can be like an out-of-control roller coaster ride and when there's no one else to turn to for support or a second opinion, I go undercover to blog about the everyday dramas of raising my otherwise perfect teens.