McClaren, who celebrates his 49th birthday on Monday, took charge at the club in June 2008, six months after he was sacked as England coach in the wake of the national team's failure to qualify for Euro 2008.
Talking about his time as England boss, McClaren said: "You need failures to make you stronger. I had a massive one.
"There's not a day goes by I don't think about it. I hope this draws a line under what's gone before."
Twente finished second in the Eredivisie in McClaren's first season, and were runners-up in the domestic cup final.
But they went one better this season, pipping in-form Ajax to the post, and earning themselves a place in the Champions League group stages for the first time.
Facing an NAC Breda side hoping to qualify for the Europa League play-offs, Bryan Ruiz - a £4.3m signing last summer - settled Twente's nerves with his 24th goal of the season.
That came seconds after NAC's Csaba Feher was sent off for a two-footed tackle on Theo Janssen.
On-loan Chelsea midfielder Miroslav Stoch sealed the win 16 minutes from time.
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