DS1 is 18, in sixth form. He was in a long term relationship of over a year which ended in January. He struggled with this massively, was depressed and very upset. It was a bit messy from what I can tell as she stayed a night in February, but we haven't seen her since.
Today a friend who's DD goes to school with DS informed me about some rumours going about in regards to DS behaviour. Apparently he is harassing his ex, calling her on no caller ID, hanging around outside her classes, shouting at her on her walk home from school saying she's slept with another guy in earshot of everyone. My friend thought it's better we know and talk to him.
I mentioned it to DS tonight, he told me it's not true and people are stirring it and he only wants to talk to her. I told him he's not entitled to talk to her if they have ended the relationship. DS2 stepped in (he's the year below) and told me that he's made fake instagrams to watch her stories without her knowing and checks it loads every day. In DS2s words "he's obsessed and creepy".
DS1 maintained this isn't true and everything's fine.
I've told DH about it and suggested he has a man to man talk, but DH says If DS says it's not true we need to believe him and have his back, even if it was true he's 18 it's not our business. AIBU thinking this isn't good enough and he should step up and have a chat? I'm ashamed of DS if he really is harassing this poor girl and not respecting boundaries.