Speaking to The Sun, the singer confessed she is in constant contact with her Girls Aloud bandmate. "I am completely devastated, it's been really, really tough, but speaking to her a lot helps and keeping that contact," she said at the Sleepless musical premiere.
"She's a strong girl and I love her so much," the star added.
WATCH: Kimberley Walsh on how fame has affected her life as a mum
It's been one week since Sarah, 38, shared a picture from her hospital bed, explaining that she was diagnosed with breast cancer earlier in the year and that the disease has now spread to other parts of her body.
"Earlier this year I was diagnosed with breast cancer and a couple of weeks ago I received the devastating news that the cancer has advanced to other parts of my body," she told her followers. "I'm currently undergoing weekly chemotherapy sessions and I am fighting as hard as I possibly can."
Last week, Sarah confirmed she has advanced breast cancer
Thanking the NHS for their care, Sarah added: "My amazing mum, family and close friends are helping me through this, and I want to say a thank you to the wonderful NHS doctors and nurses who have been and continue to be heroes.
"I am doing my very best to keep positive and will keep you updated here with how I'm getting on. In the meantime I hope you’ll all understand and respect my request for privacy during this difficult time. Sending you all so much love….xx."
Girls Aloud split up in 2013
Both Kimberley and Sarah rose to fame in late 2002 when they auditioned for the ITV reality series Popstars: The Rivals. The pair then won a place as members of the girl group, Girls Aloud, alongside Cheryl, Nadine Coyle and Nicola Roberts. The pop band parted ways in 2013.
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