Please help!!! Please read! Very serious.

What do you do if someone is accusing your child of molesting and/or sexually abusing theirs??? This is my 11 year old daughter and my 8 year old niece. I don’t know what to do. Her parents won’t even talk to me I’m getting all communication about this via mine and my brothers mom. They’re making it out like my child is a monster. I’m just trying to sort through this without scaring my daughter.. but my main concern is if something happened, and my daughter DID do this, then that means something happened to my child.