Once the initial treatment period is over, many women conclude that the time between getting the first diagnosis information and then starting treatment, is one of the worst times to be going through in this journey. If you can, please accept the reassurance that what you are feeling right now is completely normal and understandable. You will get past this bit and you will be starting treatment to zap the bugger very soon now.
I remember the racing extremes of emotions that I went through at this stage, and for me it got worse after I saw the oncologist whilst waiting for treatment to start. Every ache, twinge, cough, mole, lump, change became for me, a potential symptom that it had spread. (It hadn't.) Every blood test, scan, health conversation in that time period was me second guessing whether there was a much bigger problem. (There wasn't.) I did quite a bit of crying and some shouting. I would start off the day strong have a wobble and crumble and then terrify myself on the internet and crumble some more, then try to scoop myself up. Rinse & repeat. I just wanted to go into hospital and have it all taken out of me tomorrow. (That wasn't even an option for me, I had chemo rad.) All these feelings are normal. It's a scary, tortuous time, but you will come through this.
If it helps, the time between seeing an oncologist and starting my first treatment was about three and a half weeks and then the actual treatment took up most of my thoughts instead, which was a blessed relief.
It's easy for me to say from my vantage point right now, but try reframing things with, 'Thank goodness they've diagnosed it, now they can get on with treating it.' A massive team of people with tremendous expertise are using all their skills to help you, and hopefully you have close family and friends who will join that team with practical and emotional support too.
As for the internet, lots of people say stay off Google and come here for info. It's good advice, but I haven't met anyone yet who managed to stay off Google so I'll just leave this here. Statistics and survival rates are generally based on information gained between 5 and 10 years ago. By the time you read them online, they are already hugely out of date. Chemotherapy drugs and optimal dosage regimes change all the time, radiotherapy machines are more sophisticated and the accuracy of scanning is better than ever before. If you find yourself googling away and scaring yourself silly, try and haul yourself off that page and go and do some small kind thing for yourself. You are a unique, fabulous individual, not some statistic on a chart.
Instead of torturing yourself with 'What will my family/kids do if I'm not there?' try 'What practical things can I do now to help my family help me whilst I'm going through treatment to sort this out?' Try not to bottle everything inside all the time, identify someone you can talk to and trust with your feelings & fears. For me, it was my husband, he was scared too and trying to be strong for me, but it was much easier to get practical things done when we were being honest about where we were in the roller coaster each day. (...and sometimes each morning and each afternoon!)
Cry when you must, hang tough when you can, but be kind to yourself too. It's all good. You will come through this time.