Geez. It's like you're their hobby. I know it's sometimes dangerous *not* to be aware of the nastiness, but in your shoes, I think I'd just make a habit of "delete unread." Paying attention or ignoring--it's a tossup which gets them more torqued. But at least if you're not reading it it's not affecting *your* mood.

I'm sorry, you didn't really ask for advice. I'm just sympathetic and more than a little angry on your behalf.