Hello! Please remember that my response is for information only, we are not establishing a therapeutic relationship.
When there is "reasonable suspicion," that a minor child has been abused, then a Mandated Reporter must report. You said this was 12 years ago. If that child is now 18 or older, then the abuse is only reportable if the perpetrator has current access to children (such as other children in the home, he/she is a teacher, etc).
A report can't be made without all of the pertinent information (name, and at least a phone number, address, etc). If a Psychologist does not have this specific information, it's impossible to file a report.
If for example it was your brother (as molester) and you tell the therapist that he lives with you and give his name, you've given enough information. If it was a "cousin," and you haven't given any identifying information, that's not enough to make a report.
You need some help around this issue. I know that it can be difficult when someone we love/care about does something as heinous as molestation, however, there's can be a great "cost" to "protecting" them --if they offend again, and for the victim who might be either feeling completely abandoned (no one reacted to what happened to me) or confused (I think something happened, how can I tell for sure)? Either scenario is extremely damaging for victims. While it's true that there's not much empathy for perpetrators (which hinders some from getting the help that they need), it's not a reason to protect them.
Let me know if that's not clear enough (about the confidentiality) and I will clarify.