The Reds saw their 20-match unbeaten league run go up in smoke at the Pirelli Stadium, losing 3-1 to hand Sunderland the initiative in the automatic-promotion race.
Burton also had their say in midweek, holding the Black Cats to a 1-1 draw at the Stadium of Light.
But the result was enough for Sunderland to leapfrog Barnsley into second place, moving one point ahead with a game in hand still.
And Tonge wants the Tykes to get that disappointment out of their systems ahead of the final five games of the campaign.
“It has been a really positive week and I think a lot of people have made a lot of assumptions about what might be happening with us now, but the players have been excellent in the last few days,” assistant coach Tonge said.
"The attitude in the camp has been really positive and it has been great to see, to be honest.
"With our recent form, we can be honest and say it has not been our best. But at the same time, the monkey is off our backs now.
"I think if there was ever a time to lose, it was last weekend and, from our point of view, it gives us the incentive to create better momentum going into the last few games.
"It has been a week of reflection and saying: 'look we have not been at our best in terms of results and performances have not been what we would like.'
“Maybe Burton highlighted those weaknesses and they got their rewards.
“We must do better in all areas and defend as one and attack as one. It is something the gaffer has highlighted all season, and we have not been doing that.”
Barnsley need to regroup as they welcome Fleetwood to Oakwell, where they are unbeaten this season, on Saturday.
The Cod Army are safely positioned in mid-table in Joey Barton’s first campaign at the helm, but have collected seven points from their last three outings.
“They are obviously a team that love to play football,” Tonge said.
“They have tweaked their style, going to a three at the back, and they have got results from that.
“They are a very positive team with some good attacking players.”