Antonio Brown is no longer a Pittsburgh Steeler ... and there's one superfan who's still trying to figure out what to hell to do about losing his favorite player -- that guy is Carson Kressley.

Yes, as it turns out, the 'Queer Eye' star -- an Allentown, PA native -- is a HUGE Steelers fan. Seriously, the dude even has AB's total yardage memorized like some kinda freak.

So, with CK being the biggest AB fan east of the Mississippi, we had to ask the fashion guru how he's handling the news of Brown going to the Silver and Black.

And, uh ... let's just say he's had better days.

"I can't believe it," Kressley tells us in NYC. "We're gonna miss him. Antonio, come back to us, please!!!"

There are fake tears, hugs, and compliments shared as our camera guy consoles the devastated Kressley ... and it makes you almost feel bad for the dude.