she's been cat-fishing people

I don't really know where to start, but my cousin downloaded an app where she talks to men from Korea all day. She has multiple boyfriends that she talks to & just recently one of them came to me to tell me what she did. So I get this weird message from someone saying that they need to urgently talk to me over my cousin.I responded and he starts to tell me that they dated for six months & she told him things about me, my family and made up stories about one of my cousins raping her. At first I didn't believe him, but then he started sending me pictures that she took of me and sent to him (I know she took them) pictures of my daughter & he said she event sent pictures of my ex. He somehow knew everything about my life which was WEIRD. He then told me that she used photoshop to make herself look different after seeing a picture of us on my profile. In her photoshop pictures she looks skinny (she's over weight) & her face looks different. There were even some nudes.. I was so creeped out. I tried talking to her about this but she always blames the guys for being crazy & stalking her.. which I learned is false. I'm really worried for her bc she's messing around with people & if she messes with the wrong person something might happen.. should I tell her parents about this? Talk to her sister? I really don't know what to do to make her stop doing this, I'm also really upset that she involved my daughter & myself in this whole thing.. like why do these guys need to know about me/life?