Verity Rushworth says it was "very emotional" when Donna Dingle told ex-lover Marlon she had cancer.
The actress - who left the soap in 2009 before returning last month - admitted she and her co-star Mark Charnock found the scenes difficult to film.
She told What's On TV: "That was a heavily emotional day. In the space of one episode, Marlon and Donna go from shock, through to anger and then the emotion comes out. I really poured my heart and soul into it."
Mark agreed the scenes were "upsetting" and "affected" him, even though he knew he was playing the part of a character.
He admitted: "It was upsetting. I am not a method actor, but you can't help but be affected by a story like this, especially when you see April who looks like a little Verity.
"It also felt like such a big responsibility. I wanted to get it right because this happens to people."
However, he still uses his own "sad" experiences to help his performance - and the bond the two actors share helped make the moment more real.
He added: "It really helps that I have a bond with Verity. We get on really well, so it is easier to access that chemistry.
"I like a laugh and a joke on set, but when I am doing scenes like that, I can't do that or else I lose the 'truth' of what Marlon is feeling. I do prepare myself by thinking of sad things that have happened to me."
Tagged in Verity Rushworth Mark Charnock