In devastating scenes predicted to air over the festive period, Sinead is said to hear of her husband's infidelity just days before she dies.
Stock up on tissues!
Next week, Sinead and husband Daniel Osbourne's worst fears are realised when her consultant breaks the news that the cancer has spread to her lymph nodes and liver.
The brutal truth is that Sinead is given a prognosis of only three or four months left to live.
Sinead will discover a lump on her neck on her wedding day on Monday September 9.
The terrified couple will go to the hospital the following day where they are given the horrific news her cancer has returned.
She's going to be devastated when she finds out what he did with Bethany.
As the couple grapple with the reality and the thought of their son Bertie growing up without a mother, Daniel has a guilty conscience after sharing a forbidden kiss with Bethany Platt.
Now, according to a report in TheSun.co.uk, Daniel will confess all to Sinead on her death bed.
A source told the website: "Sinead wants to do everything she can to make her death easier on Daniel so he can best support Bertie.
"She's going to be devastated when she finds out what he did with Bethany and really struggle to get through it knowing she only has a limited time let.
"Daniel has put her through a terrible ordeal by normal standards but, with only weeks left to live, it's the worst thing he could have done to her."
Katie McGlynn, who is leaving the ITV soap after six years playing Sinead, recently thanked fans after her character's sad storyline was confirmed.
She said: "After nearly seven wonderful years playing Sinead Tinker, my time on the cobbles is coming to an end. I feel so privileged and honoured to have been part of Coronation Street.
"I've honestly enjoyed every since second working alongside a BRILLIANT cast and crew who go above and beyond to make Corrie the amazing show that it is, I'm going to miss everyone so much."
Katie then added: "I'm sad to be leaving Sinead behind, but I felt the time was right for me to spread my wings and pursue other opportunities.
"As a team we felt Sinead's ending on the show should highlight the importance of cervical cancer screenings - and that women NEED to go for their smear tests."
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