The Swans saw Kyle Bartley sent off early on in the FA Cup tie before Gylfi Sigurdsson was also later red carded as Blackburn ran out eventual 3-1 winners.
It means they will be without their star midfielder for their upcoming Premier League games against Southampton, Sunderland and West Brom - and completes what has been a nightmare week for manager Monk after the heavy loss to Chelsea.
“When you go down to ten men so early, all the preparation you do in the week goes out of the window,” he said.
“And it's meant we've gone out of the cup which is very disappointing because we wanted a run in this competition and we wanted to bounce back from last week.”
The manager has also admitted that he is unsure whether the club will appeal both red cards, hinting that he doubts any appeal would be successful.
He also hit out at both stars for receiving the red cards, both of which saw Swansea’s sending-off tally rise to a league-high eight for the season. Former Arsenal man Bartley came in for particular criticism, with Monk, a former defender himself, saying the Swansea man simply failed to get his positioning right early in the game.
“Kyle should have seen the danger coming,” added Monk
“All they were looking for was long ball over the top and centre-halves need to get the right positioning early in a game and Kyle didn't.”
Swansea were not alone, however, in losing to lower-league opposition in the FA Cup on a Saturday that will go down in history for its shock value. Both Manchester City and Chelsea lost to lower-league opposition, while Tottenham were beaten at home by Leicester City and Liverpool drew 0-0 with Boolton Wanderers.