Respect their need for absolute confidentiality. Not making their secret public may be the only safe thing for them to do as they see it. If a person who you confide in presses you to identify the survivor, do not tell them. If you help make the details of the assault public, you will do the survivor harm. Don't assume that the level of disclosure that you shared previously is acceptable currently or later when you talk to that person.
Some survivors never bring it up again.
Some refuse to talk further about it. Some even avoid you. This doesn't necessarily have anything to do with you. You might be the only person they have confided in and every time they see you they recall their abuse. Don't punish them for your feeling of being used if that is how you feel.