Hi @tisme. This is a dreadful time, and as everyone has said, take it one day at a time. One hour at a time even, if necessary. This is a technique that counsellors recommend. It helped me when I was first diagnosed and a wreck.
'Predictive grief' is a phrase my psychologist uses and urges me not to do! Easy to say but harder to do I know... Being prepared is one thing but anticipating troubles that may never happen is no way to live. So focus on today, take some deep breaths (it settles the nervous system) and be kind to yourself.
Being diagnosed with breast cancer interrupts our lives no end. It was pretty disastrous in my house (click on my @name to read my story). It's always disruptive, be it for a few weeks or a year. However it's a very well oiled treatment machine and there are huge amounts of support and services available. And if you're diagnosed and undergo treatment, you'll be surprised how quickly it becomes routine.
So hang in there. Big hug, K xox