<human>: Can you give me a shortened version of the text?

Hello. So, I need some help here concerning how to report an issue of underage sexual activity. I need most help concerning how to go about reporting it and concerning the legitimacy of it. Here is some back-story that should help, as this needs to be addressed in a respectful and sensitive manner. I hope that this post doesn't fall too far into a "relationships" issue. I am a male (17) and used to be quite good friends with a female (14) student that went to my school. We were quite close friends at the time. A few months ago she went to a male (18)'s house and spent the day with him at his house. She later (a few days) confesses to me that he fingered her and that they "dry humped." This concerned me greatly and I wanted to report this. I, however, let it slide and tried to move on from it. This soon became a rumour that went around the school, as well. From then to now, we have lost our friendship. I just found out, however, from a friend of hers that she is now saying that she gave male (18) a blowjob. For her own good, I feel now that this is something worth mentioning to a "higher power." NOTE: Her parents do not know of her activities. So, my biggest issue is how or if I should report this. Report it to the males work? To the school? To the police? To her parents and let them deal with the issue? I apologise if this belongs on /r/relationships and I will remove it accordingly if I am notified that it should be. We live in Southern Australia. She is legally underage for this form of sexual activity. The other issue is that I do not have any evidence that this happened. Just her word and (possibly) that of male (18). Thanks
<bot>: Female (14) apparently got fingered and gave a blowjob to male (18). How should I report this issue? Where to and how do I deal with a lack of evidence?