Some things they can say are:
“Thank you for trusting me with this”
“Is there anything I can do to support you?”
“I know a good resource we can call, do you want me to call with you?”
“It wasn’t your fault.”
Some things to not say:
-don’t ask them if they are sure
-Don’t share what was shared with them unless it is to a trusted adult for support for themselves or to get help for their friend if they are in danger