Dear Vallerina
It is scary, it is confronting, it is devastating. It also is what it is. When I was told my breast surgeon (brand new acquaintance) wasn't happy with my mammograms and ultrasound (no inkling, no lump, just a funny slightly sore feeling) his nurse told me that if you have to have cancer, breast cancer is best because your survival chances are greater. 4 years on, and feeling pretty good, I think of all the things that I would have missed in my life if it had been cut short then. Not how cancer cut short the things I enjoyed. It can take a while to get your head to that place, but it's worth trying to keep on that side of the equation. Your plan sounds really sensible - take one step at a time. I know a mastectomy sounds terrifying (I had one and lost a lot of lymph nodes too) especially after you have come to terms with a lumpectomy, but there are lots of people here who can give you support and advice about the surgery and reconstruction. It's normal to be anxious - but step by step people negotiate this, deal with treatment (howling and swearing is almost mandatory!) and get on with the important things in their life like marriage and grandchildren (my second is due in July too!).
Keep breathing, and focus on getting through it all. Best wishes.