<human>: Can you give me the gist of the text in a nutshell?

Little more info, in a long-distance (well four hour bus journey) relationship. During a rough patch the SO was being chatted up by some guy and almost got with him but didn't when she realised she only wanted me (r/cringe, etc.).

This is all fine, but afterwards he started telling people she'd slept with him, and when I was visiting for a weekend he messaged her on facebook with further weird statements, like "I miss you in my bed" and such. All this made her very upset and as a result, I have decided to do something. I don't want to resort to violence but I do want to scare him. Help would be much appreciated.

From looking through his Facebook photos I can tell you he goes to Trinity College in Dublin, he likes designer clothing and he's visited Rome. That's all I got I'm afraid.
<bot>: some bag of piss spread rumours about my girlfriend, how do I destroy him in a non-physical manner? I don't want him actually harmed or in any real danger, just scared.