My son is 10 and has a WhatsApp class chat. I tend to check it every few nights or so and everything has been fine. They talk about weekend plans, class trips etc. I went through it last night and felt sick to my stomach where he had been posting in the group chat stuff of sexual content..mostly aimed at this one girl. I am horrified. I'm not sure the mum knows yet so I'm not sure whether to message her apologising. I'm pretty sure the school is going to get involved as well? I have no idea where he has picked up this language. He's generally well behaved bar the occasional strop and has a good social life and active. I don't know jow to navigate this at all. Can anyone advice please.