Town beat Barrow 3-1 to move up to 80 points but Bristol Rovers thrashed Scunthorpe 7-0 to overturn a five-goal deficit and win promotion by the virtue of scoring more goals over the course of the season.
Sam Hoskins scored twice and Fraser Horsfall headed in another as Cobblers raced into a 3-0 lead at Holker Street before things began to go awry.
"It’s pretty hard to comprehend right now,” admitted a forlorn Brady. “That’s all I can really say on it.
"I thought we were excellent. We started really well and to go 3-0 up after 20 minutes was the perfect start.
"They made a couple of changes and then started to get back into the game but for their goal it’s a clear foul on Shaun McWilliams.
"We have turned a lot of moments around this season. I’m still trying to comprehend it but we will dust ourselves down and get ourselves ready for the play-offs."
Scunthorpe fielded a bunch of teenagers against Bristol Rovers, including a 17-year-old goalkeeper and an 18-year-old captain.
"Barrow fielded a full-strength side today and they are a good team,” Brady added.
"I don’t want to say anything on the matter with Scunthorpe. It doesn’t concern me and I need to look forward and we need to look forward.
"Whatever’s done is done, whether it’s right or wrong.”