A 3-0 home drubbing at the hands of an excellent Brighton, shortly after City dispatched Everton by the same score, all but extinguished Arsenal's dream.
It all felt hugely anti-climactic with thousands of Arsenal fans having already headed for home with Brighton 2-0 ahead thanks to second-half goals by Julio Enciso and Deniz Undav.
And when Pervis Estupinan made it 3-0 in stoppage time in front of a rapidly-emptying stadium it all felt rather embarrassing for Arsenal, who led the table for large swathes of the season but have buckled over the last six weeks.
"A week ago I was standing here feeling proud and today we have to apologise for the performance in the second half. It was not acceptable," Spaniard Arteta told Sky Sports.
"Mathematically, (the title) it's still possible, but today it's impossible to think about it.
"We need to digest the result and the performance in the second half, understand why and have a different reaction."
When Arsenal beat Leeds United 4-1 on April 1 they were eight points clear of City and in control of the title race.
Since then, however, they have managed two wins from seven games and were taken apart at City last month.
Arsenal have made huge strides this season, having come fifth last time, but a glum Arteta could find few positives after his side's second-half capitulation against Brighton.
City's win at Everton in a game which had looked like a potential banana skin for Pep Guardiola's side flattened the mood even before kickoff and Arsenal's display, especially in the second half, was arguably their worst of the season.
"(City's win) cannot be the way to justify what happened in the second half," Arteta told reporters.
"At the moment the feeling is frustration. That we gave the game away. We fought really hard to be in this position and today was a critical moment to keep hoping and to keep digging for the dream. But you can't do what we did in the second half."
Arteta said he has a "lot to think about" over the summer as next season will see Arsenal juggling the Premier League with the demands of the Champions League.
But for now, he needs to pick his side up for next Saturday's clash at Nottingham Forest, when defeat will confirm City as champions.
Even if Arsenal win, City need only one win from their three remaining league games.
"I hate the feeling of letting people down when they are really expecting something," Arteta said. "That's the biggest regret that I have today. And we have to apologise for that."
