Scared, confused and need advice

Hi, I don't even know where to start or what to say because at this stage I don't really know anything - I had breast cancer 6 years ago mastectomy chemo and reconstruction. To me it was the past something that happened, I know in the back of my mind I always knew it would come back but know the reality is here... It's just too hard to cope. I feel fine but having had to find a new doctor he sent me for tests to get to know my health and tests started coming back abnormal now a CT scan shows extensive liver metastatic disease. I only know this so far because the report was in with the scans I need to take to the Oncologist on Monday ...I am numb scared... Thinking I won't even see Xmas... I have a 3 week holiday booked for next Friday with a girlfriend we have been planning it for a year I have had a really bad emotional and stressful couple of years... I was waiting to come back to do my yearly scans etc ... Does anyone have any advice on waiting 3 weeks to start treatment if that would be ok... I know this should be the last thing on my mind .. But I think if I only have months I should do everything I want to do while I feel good .. But then I think can I become really sick in a week or 2 ... I feel I am going insane!