For context, DD has always been more of a 'follower' type of girl and for some reason, has always friends who use her and then, act really nasty. But this particular incident is a first time for all of us.She was crying non-stop yesterday. DD, 11 y/o, has moved into secondary, but tried hard to keep in contact with her previous mates from primary, who apparently dont want anything to do with her. So, after some exchanges, this primary friend of hers decided to create a group on snapchat adding various kids, many of them who don't even know DD nor does she know them, and started writing the most nasty-est things I have literally ever read. Swearing at her, and mentioning things like 'fatherless shag', I mean absolutely awful. Things that I could not believe have come out of an 11 year old child, but there you go. And distributing her picture, which she shared with her a long time ago, talking about how ugly she is to people DD doesn't even know!It's absolutely horrible and I don't even know what to do. We have blocked them all, but chcked this morning and she is still being added in yet another group where the girl is mentioning her again. On top of that, she has threatened her that she'll knock on DD's door and beat her up. I don't want to take that as a joke as there have been some incidents around us where girls have beaten up one of their friends, and I'm so so scared. Husband is thinking of maybe taking some legal action, but I have no idea which is the best course of action.Should I just mention on the group that I'm the parent who's talking and if they don't stop, legal action will be taken? Or should we just ignore them? And what about safety issues for DD? I have been telling her in the past few days that she can come alone from her school, but now I'm scared and I will have to pick her up as well as not let her hang out alone outside. It's just horrible.Any help or advice very much appreciated!!!