Goals from Christian Benteke and Charles N'Zogbia ensured Villa took all three points to move out of the Premier League relegation zone, despite Ashley Westwood's late own-goal.
The 2-1 win was Villa's first win in nine league games, having managed to accrue only three points from the previous 24 available.
"It's a huge win for us," admitted Lambert. "We have been in positions of being goals up in a few games.
"If we had taken more points from those, we'd be comfortably in mid-table. But the pleasing thing is we have hopefully broken the camel's back with that.
"It's only great when you hear that whistle and you've won. It's the only good thing about it. The stress levels are ridiculous.
"It's hard to explain. You have to be in that position. Balls are going into your box. But once it's finished it's great you have won. You just have to see it through."
Lambert was particularly pleased with the contribution of N'Zogbia, who scored Villa's second - a superb free-kick.
"The free-kick was world-class, an absolute world-class goal. He's got that in him," added Lambert.
"He's a really talented footballer. To be fair, over the last couple of months, Charles has been excellent. He was unlucky because he had a bad injury with his knee.
"That kept him out for six weeks or so. Since he's come back into the fold he's been excellent. He has been very good. He's got that X-Factor. These type of players are not easy to come by."