I'm usually on the receiving end of the terrible cheating girlfriend equation, but this time I'm accidentally on the other side.

So, I'm gonna really really tl;dr this because its a mess and is far too much to type.

tl;dr - Didn't know girl A had a boyfriend. I had no interest in girl A. Shes pretty, but dumb as a rock and just completely not my type. Girl A is also known for being a bit...mmmm..."lax" in her morals. So as a man who can only take so much, some things happened. I'm now in a position where I'll probably never see girl A again unless I accidentally run into her at a grocery store. She was working nearby me but got a different job and is gone. Whatever, I figure I dodged that bullet anyway.

So, a week later I get a buttload of threatening emails from her stupid boyfriend. Fear is not the issue here, hes a tiny man and my safety is my last concern. I tried explaining to him rationally that it wasn't my fault. I had no idea she was in a relationship, and casually mentioned I wasn't the first, and probably wouldn't be the last. I left it at that, and have gotten a few more nasty messages.

All I can do is ignore it, right? I know the guy somewhat, and hes not the type to hunt me down. I think his pride is hurt and he just needed to make some empty threats. I'd like to calm him down, but I doubt there is anything I can say to him. If anyone here knows a good way to deal with this, I'd really appreciate some help.