The actress and reality TV star, whose battle with substance abuse issues has been highly-publicised over the years, said she does not want to die and that she is determined to get better, but that she took cocaine to cope with the news initially.
Westbrook, 44, said that her thoughts turned to her late friend Jade Goody, who died in 2009 from cervical cancer.
She told the Sunday Mirror: "I've always said I am not scared of dying. But when the doctor said, 'You have cancer', straight away my thoughts turned to Jade and that I don't want to die. I know I need to fight."
Westbrook, who once spoke to Premier about how she became a Christian, said her mother was diagnosed with womb cancer 30 years ago, and that she is "still here" thanks to undergoing treatment on the NHS and that she will follow suit.
She added: "They are taking me in in three weeks for a full hysterectomy. Before they take it out they won't know to what extent the cancer has grown."
Westbrook said her doctors believe the cancer is "containable so I'm hopeful".
Westbrook, who rose to fame in the 1990s playing Samantha Mitchell in EastEnders, said the cancer was diagnosed by a doctor in Spain, where she lives, after weeks of heavy bleeding and being unwell.
She said she was told the cancer is "behind the uterus wall and that's why it's not being detected".
She then returned to the UK, where she said a doctor in Essex confirmed the disease.
Westbrook said that she partied in Spain after hearing the news for two days, where she "used cocaine" because "I wanted to numb everything and get drunk", something she said she now regrets.
In 2016, she relapsed into taking drugs following her successful stint in Celebrity Big Brother due to a bout of ill-health.
Last year, mother-of-two Westbrook said she had suffered a miscarriage, and that it was one of several over the years.
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