Crushed Over Russ Wilson Trade

Breaking up is hard to do -- just ask Seahawks super fan Joel McHale ... who's not doing so well after finding out his favorite team shipped away star quarterback Russell Wilson to the Broncos.

TMZ Sports spoke with McHale out at LAX on Friday afternoon -- just a couple days after his Seattle squad parted ways with Russ -- and the comedian told us he's been pretty down in the dumps over the trade.

"I'm just as surprised as you are," McHale said. "I thought he was staying. Clearly, I was wrong. That was shocking news."

Joel had previously told us he thought there was no way in hell the 'Hawks would deal Russ -- but now that they have, he said he's downright sad.

"He's one of the best ever," Joel…