had to file a report/student feels upset

This post isn't about my own therapy, but one of the at-risk students I work with (ages 11-15). I mentor these kids one-one-one every week in a school environment, and they've come to trust and confide in me. Well this week, one of the girls shared something about an adult relative punching her and pulling her by her hair. She says it had already been reported and happened "a long time ago", but I mentioned it to my LCSW supervisor because that's the kind of thing I have to tell her. Apparently the way the law is in my state, I still have to report it to CPS.

Since this is one of my older, more mature students, I outright told her that I would have to file a report, and she's understandably pretty upset. I have few details and made it clear on the report that the perpetrator does not live with the girl, does not have much contact with her currently, and that I do not suspect anything is ongoing. This particular student has been taken away from her mom in the past, so she may be worried about that happening again though I do not expect that to happen in this case. I think she's pretty upset and maybe even feels betrayed or that she can't trust me, but I'm legally bound to report it (and already did).

Any advice on how to approach the student the next time we meet and help her through this? And how do I handle the stress and guilt of one of my students (all of which I care for) being upset with me bc I have trouble with being a people-pleaser? I'll try to talk to my supervisor a bit more about it, but I don't think she quite realized how affected I was by this.

Let her talk about how betrayed she feels without trying to defend yourself. She understands logically that you had to report it, so now she needs you to understand why she's so upset.