WHO do I tell?

I was and still am in the same situation.  I'm incredibly private and telling too many people will overwhelm, you so do it very slowly.   You also need to be mindful if you're making big decisions about chemo etc. If you can somehow   find others who've had breast cancer they will be much better to bounce off.   Whatever you do I found this process very stressful.  I actually confided mostly in alternative health care professionals like a masseur, acupuncturist or similar.  They should keep your confidentiality until you're ready to tell people.   I didn't tell any neighbours at all.   I'm not sure if this was a mistake as I did end up quite isolated.... but I also didn't have well meaning people knocking on my door offering help.   If there's a therapist that specialises in cancer at whatever clinic you are at they are worth their weight in gold.   Don't know if this helps but I hear you.