Second-half goals by debutant Francois Zoko and Filipe Morais ensured the hosts went through to the quarter-final stage of the Johnstone's Paint Trophy Southern Section for the first time.
The tie looked to be going to form after a Shaun Williams penalty gave the Dons the lead but Stevenage, who are struggling in League One, were to avenge their 4-1 defeat at stadium:mk last month.
Westley said: "It's been a long time coming and we've been on a horrible run of results where the team hasn't looked like it's had a win in it.
"We got arguably our most experienced players on the pitch with one or two coming back from injury and I think the players showed a lot of quality.
"More importantly to me, they showed a real appetite to win a football match and you've got to have that fighting spirit.
"It felt like the good old days for the first time since I came back to the club.
"We know Zoko is capable of scoring goals - he's not got a prolific ratio but certainly at League One level he can put the ball in the back of the net.
"It was just so refreshing to see a guy pop up in the right place at the right time and totally release the pressure on us."