Coronation Street - Cathy Matthews is left fighting for her life after discovering her sister Nessa's betrayal.

Cathy will be heartbroken when she stumbles across the incriminating letters that reveal Nessa had an affair with her late husband Alan.

To make matters worse, Cathy is horrified that her partner Roy also knew the truth and was helping Nessa to retrieve the evidence to prevent her from finding out.

A heartbroken Cathy vows to never forgive Nessa for her betrayal, but tragically applies the same treatment to a devastated Roy as she calls off their relationship.

Melanie Hill, who plays Cathy, said: "She is devastated and feels extremely let down. She feels as though Roy has made the betrayal worse by siding with Nessa. Of course that is not what he was doing, he was trying to save her the heartbreak of finding out but she is so upset she can't see that. She was very happy with Roy. It had taken her a long time to get over Alan's death and move on and she really was starting to feel like this was a new beginning for her which is why this hits her so hard."

As Cathy reels in the wake of her discovery, disaster soon strikes when a fire breaks out whilst she is attempting to burn Nessa and Alan's love letters in the bin. 

As the fire starts to take hold, Cathy struggles to breathe, but Roy, who has arrived at her house in a bid to put things right between them, saves the day by rushing in and getting her.

Cathy then collapses in Roy's arms as she thanks him for saving her life, but will his heroics be enough to bring the couple back together?

Hill said: "If it hadn't been for the fire I think it would have been a much longer road back for them but something like that puts things into perspective and I do think they can find their way back from this setback and grow stronger as a consequence. Nessa is a different matter altogether. Blood is thicker than water but her sister has committed the ultimate betrayal and made a mockery of a large part of Cathy's life. It will be interesting to see if anything could make Cathy forgive her. She does care about Alex so she will keep in touch with him."

Airs Monday January 4th, Wednesday January 6th and Friday January 8th