@Klp
You poor thing, we have all been there, its a very scary place. Hang on and get through this bit and then things will start to feel more normal again. Once you start treatment as everyone has said you feel like you are doing something. Chemo is hard and long but very doable. I am just out the other side and feeling well.
My advice (which I try to take myself!) is to put off the worry, wait till you have all the facts and then look to the positives, these days the prognosis for breast cancers is so much better than in the past and there are more great drugs that help you to tolerate the treatment.
My other advice is when you can, and harder with small kids, get out and exercise, go for a long walk. Its great for taking the edge off that excess adrenalin floating round your system and making you panic. I hope you feel better soon xx