I've lurked on here for a long time, and I'd like to thank you all 
I don't want to out myself, but the subject was a horrid, victim-blaming fantasy about beating up an 'arrogant' woman.
The gist of it was, women: know your place, or else!
I was so incredibly angry he'd had the nerve to think it's ok to say these sorts of things out loud to people. The more I think about it the more it sounded like a threat.
I told him off, thanks mainly to the posters on here who regularly hand MRAs their arses on a plate. Perhaps he was surprised at mine and other's reactions ... I'm not sure why he would have shared something so offensive if he knew how beyond the pale it was.
I thought people were only like that on the internet - has anyone else had an experience like this?