As the hunt for her late best friend Heather's killer continues, Phil (Steve McFadden) will continue to secretly protect guilty son Ben (Joshua Pascoe) from the police.
Speaking to Soaplife, Henry admitted that the truth about Phil's deception will "feel like the ultimate betrayal" to her alter ego Shirley.
"She'd be absolutely distraught," she added. "She and Phil have been through thick and thin and when he told her he would do anything to stop the hurt she was feeling, she believed him.
"She'd know that Phil would feel obliged to protect Ben because he is family, but I don't think she'd forgive him for it."
In tonight's edition of the Albert Square soap, Ben comes close to confessing to the murder during a talk with his psychiatrist.
Later this week, Shirley discovers that Heather's suspected fiancé Andrew Cotton (Ricky Grover) is not her murderer
> EastEnders Shirley Carter to face fresh heartbreak