Hi Broni. So sorry that this is happening to you. You've got some excellent advice already from the wonderful folk here. I've tagged you in another post I wrote moments before I read yours, but I want to add a couple of things here.
Try not to worry about being positive. If you are, that's great, but don't force it. It makes no difference to your medical outcome (one of my oldest friends conducted the study that definitively proved it didn't). If you are a positive person in you pre-BC life then it will help you feel better as you go through your treatment. But there's absolutely nothing wrong with saying you feel like crap and are miserable and scared. Bottling up these feelings does no one any good. I was very angry and upset in the early days and I just wanted the pain to stop. A counsellor told me to lean into it, which I found bizarre at the time. But at almost a year later I now know that if you don't acknowledge and express those emotions, you're more likely to have difficulties later when you try to resume your life.
Of course you can't be all devastated and upset with everybody! Have a chosen trusted few with whom you can be genuinely open. It will truly help. Reaching out to a girlfriend who's been through this herself is a really good idea.
I think it's much easier to tell the wider circle of friends and then work the news when you have a treatment plan. You yourself will feel better at that point and will be able to answer the questions easier. You are absolutely in the worst bit right now, the not knowing. Hang in there. One day at a time. Big hug, K xox