Alex Cuthbert's two second-half tries were no more than Rob Howley's team deserved in what ended up being a 30-3 rout as Wales denied England not only a Grand Slam but also leapfrogged them to the RBS 6 Nations title.
And for Parling, who started all five of England's games in this year's Championship, there was little room for consolation after a Grand Slam push that fell at the final hurdle.
"That was a massive opportunity lost," he said.
"How many people get an opportunity to win a Grand Slam? And we have lost the Six Nations too.
"We showed character in Dublin and France and this team has a lot of that - but when the really big one came around, we let ourselves down.
"We were beaten in all areas of the park. They got the better of us at the ruck and were more clinical with the ball. We didn't play well.
"It hurts. We are not going to look back at the last four games that we have won and be pleased after what has happened."
As the points began to add up in the second half England looked all at sea and the Leicester lock has vowed to learn from their Welsh humbling.
"It's the first time with this group of players that we've had to stand together under the posts and say that we're only playing for pride," he added.
"Normally you can rely on one part of your game or another to get you back on the front foot. But this time all the other bits of our game fell apart as well.
"I don't know about long-term damage but the short-term damage is pretty hard to take at the moment."