Dear @susie55
The shock is understandable. Dense breast tissue is harder to scan, so sometimes very early cancer can be missed but cancer may also develop quite quickly.
Do you have family or good friends who can assist you in getting and understanding the information from your surgeon, and later your oncologist? Most people find getting the full story of their diagnosis and treatment helps in coming to terms with the unwelcome reality. The scans and tests you are having will all help in determining the best treatment for your particular diagnosis.
Can you talk to your GP about some temporary assistance with sleep? Anxiety is normal but not terribly helpful at this time. Once you know more, you might also find some counselling useful, your GP can refer you. Cancer not only affects the body but it can really mess with your emotions too - many counsellors can give excellent advice on how to cope, to reduce your stress and to get back on a more even keel. Best wishes.