Translation:I hate everybody, and you in particular.
Lovely stuff, after living in Israel for over ten years, completely understandable
Is the use of the definite direct object marker את with כולם normal here? I would have thought that the universality of "everything" would have precluded a marker of definiteness.
As far as I know every definite direct object must have the את right before it, and that includes כולם, of course. It's not superflous; it's mandatory. Otherwise, you wouldn't use את before the article ה in cases of definite direct objects.