Sorry to break it to you Karen, but you are normal! Everything you're feeling is a natural reaction to what's happening to you. Pretty much everyone here knows exactly how you're feeling. Collectively we're all reaching out and giving you a big hug.
Let those tears flow. Cry until you can cry no more. No good will come of holding them in.
One in seven women in Australia will have breast cancer. You will definitely know someone in the future who has this diagnosis.
I'm so sorry that you feel so alone. Getting a cancer diagnosis is a terribly isolating experience. That's where this forum comes in handy. Everyone gets it, there's always someone around, so let it rip. Vent, howl, get furious. You will also have lots of questions and this is the greatest hive mind around.
If you want human contact, call the BCNA helpline that @arpie mentioned above, and you can also talk to someone at the Cancer Council on 13 11 20. Speaking from experience, they're both wonderful.
In my early days I saw a counsellor at a local hospital which didn't cost anything. It was good to howl it out and get some advice on how to manage the storm of emotions. You could ask your GP about options in your area.
The sense of it being all a bad dream fades over time, but for me it still pops up from time to time. Hang in there lovely. Biggest of hugs, K xox