Thanks Moira and Plucky. It helps not to be alone on this one.
What happened today is that I got an email from these people - I was supposed to be babysitting for them tomorrow, and the email cancelled, and said they have made other plans. I rang and asked if everything is ok - as you do - and was told well no, we think you told ss on us.
I told them, no it was not me. (This is true.) Then I got a lot of do you realise how difficult this past week has been for us (the adults involved), and how they are going to talk to a x year old child about their parents, and ask what kind of parents we are. They said we are going through hell, and that we have done nothing wrong, and that a pack of lies have been told about us. To which I said, no lies have been told (I have heard the accusations from them and from my parents.). So then they said that they wanted to say things, and tell me what they really think about me, but that they would only regret it (they can't say anything about me that I have not already thought for myself, so that would not hurt at all) and then they went, and put down the phone.
However, I then rang my parents, and told them what I have been accused of (reporting them directly myself to ss) and that this is not true. They tried to say that these people won't think that way, and were surprised that I said I have been accused directly, and denied it directly, and not been believed. And so far my parents believe me. I said, first of all if I have something to say I say it. And second of all, I don't go behind people's backs. I said to both my mum and dad, if I have a problem with anyone, they will know it, and they both agreed.

The person who actually made this report is a professional, who heard things (not from me) that as a professional she felt obliged to report. She told me this is not my responsibility, and that the report is the right thing to do. I am hanging onto that.
I am also not letting any of these people play the scapegoat game, and thereby deflect attention onto who is the evil person telling tales, rather than the actual issues, which are those of preventing further harm to innocent children, and stopping that buck well and truly in its tracks.
I am not sure if I am strong enough for all this. However, we will find out.

I thought I loved these people, and that they are as innocent as the children, because they did not realise what they were doing. Now I am not so sure. The longer this denial continues, the more it is starting to stink to high heaven.