Kate,
Everything must be a bit overwhelming at the moment, but it does calm down. Even if it does come back positive, does not mean that you have passed it on. Also screening and awareness is so much better than it used to be.
When I go my BRCA1 result my geneticist put it really well, she said 'Your risk hasn't changed, just your awareness of it' This has now allowed me to make decisions about what I want to do, and entitled me to extra screening, so I now have MRIs as well as mammograms.
If you need to talk to someone the helpline is very good, there is also a specific National Hereditary Breast Cancer Helpline 01629 813000, run by a woman who has hereditary breast cancer, and her daughter as well. I haven't spoken to them myself.
The Royal Marsden also has a good booklet about BRCA which you might find useful (link below)
http://www.royalmarsden.nhs.uk/consultants-teams-wards/clinical-units/cancer-genetics-unit/pages/brc...
Hope you feel better when things have settled down a bit.
Jen