When the cancer has metasasized that means it has spread to other parts of the body, most commonly for breast cancer is bones, lungs, liver, chest. Once it has metasasized, it is a Stage IV and there is no cure only pallative care to make the patient have a better quality of life. Chemotherapy, radiation, surgery, etc. may be prescribed to help extend life, but at this point in time there is no cure for it. The average life expectancy is 18 - 24 months for someone who has been diagnosed with Metasized Breast Cancer. Depending on how extensive it is or isn't the time period could be more or less.
If you are wondering how I know all of this, I too have metasized breast cancer (spread to my liver), and will begin more treatments this month to help extend my life. I am a mother of 2; a 4 year old and a 16 month old. I was originally diagnosed with BC when I was 17 weeks pregnant with my youngest, I went through Chemo, had the baby at 34weeks, had my mastecomy, followed by more chemo and radiation. I thought I was in the clear until about a month or so ago, then just this past week, they confirmed what I thought, it had spread to my liver. I just lost my mom

in October to Liver Metasis from Ocular Melanoma. It was only 2 months from dignoses to her death. I just hope mine is a little longer.
My thoughts are with your family, I know what a difficult time this is, I've been there and are currently there.