You aren't alone, I've been hit a few times by this Steemit Defense League, or whatever the hell they're (he's) calling them(him)selves this week.

It's an annoyance, but far from a fatal one. Like a buzzing fly, eventually these accounts will get swatted, and even if they don't, the damage they can do is negligible. Your reputation protects you from attempts like this, as a flag from someone of lower reputation cannot affect your reputation in a negative way. Steemit was deliberately set up so people cannot exploit a bunch of brand new accounts doing just this sort of thing.

You'll be fine. :)