Heaslip is adamant that his side needed to take full advantage of having an extra man when James Haskell was sinbinned for England in the second half.
"We are suffering a bit in there - it is a tough one to take," said Heaslip. "England played a smart game in the conditions and played a lot of rugby in our half.
"At 6-6 they had a man in the sin bin and I really thought that we were going to create a bit of momentum but it did not go our way.
"There are a lot of lads in our dressing room feeling battered and bruised."
Ireland travel to Murrayfield to face Scotland in their next game later this month.