Coronation Street fans were angered by Daniel Osbourne's confession to Sinead Tinker while she lay on her death bed.
Sinead, played by Katie McGlynn, is expected to die later this week after her on-going battle with cancer.
The ITV storyline has been widely praised by viewers for its realism and treatment of a issue that affects so many.
But in tonight's episodes, Sinead was dealt another crushing blow as she finds out about Daniel's, played by Rob Mallard, kiss with Bethany Platt, played by Lucy Fallon.
Viewers at home were just as devastated as Sinead by the confession by Daniel - despite Ken Barlow advising him not to tell Sinead about the kiss.
Many took to social media saying they were not happy about the shock twist, @Jess_Simpson645 said: "#corrie- you are hardly handling Sinead’s death respectfully by adding in Daniel’s little fling with Bethany. Anything for a bit more drama to bump up the ratings. This has disgusted me."
Another, @brianthegeek said: "Every hour every day a beautiful woman loses her battle with the Big C, but rather than embrace that fight show the courage and bravery. And the devastating loss it has on family friends. @itvcorrie #corrie go for ratings with a tawdry story. You should be ashamed of yourself @ITV"
A third, @joy9kat said: "Ruined an important storyline with this silly 'infidelity' stuff."
A fourth, @rebeccamason12 added: "As upsetting as it’s been, this was an important and credible storyline, I fear it’s been ruined by this unnecessary Bethany addition. I don’t believe Daniel would have behaved like that anyway."
And a fifth, @raychy000 said: "Would've preferred to see Sinead have a peaceful death,understand the need for drama in soapland but feel with how well this has been portrayed it would've been a nicer ending to such a sad well acted storyline."
*Coronation Street returns on Friday at 7:30pm
