Hello. I can relate to how scared you are. I was diagnosed with invasive lobular cancer in November after screening and core biopsy. I had a skin and nipple sparing mastectomy with an expander implant put in on just that one side. Not knowing exactly what is ahead of you is really hard. I found I jumped around from worries about the cancer spreading, to cosmetic concerns, to anxieties about the best advice and treatment...
In case it is any encouragement, as one example of how things can go, in my case I was not recommended radio or chemo and now, just a couple of months after the surgery, my life is exactly as it was before my diagnosis, albeit with the addition of a daily tamoxifen piil.
I am quite comfortable with the way my breast looks even with the (weird firm round) expander in place (hopefully the final silicone implant will be a bit better still). I take great comfort from having my own skin and nipple - definitely feel it is still 'me', even though the skin is numb.
Everyone's experience is different. Personally I found the surgery itself better than I expected. I have had extremly little pain. I was at first very nervous of putting weight on that arm moving in bed, but when I was encouraged to by the nurses it was fine - for me it was just a tight muscle feeling. (An electric raising hospital bed was definitely a help - essential I would think for both arms.)
The things I found hardest to deal with were: (1) Waiting for the pathology results from the lymph nodes after surgery - you just have to keep telling yourself to deal with what is in front of you at the moment. But it is difficult. (2) Feeling very numb in and below my armpit and across my breast. I was very squeamish about that to start with, but it definitely got better each day with some reduction in the numbness and some adjustments in my brain I guess. (3) Seeing my breast in the mirror soon after the surgery looking rather mangled and deflated. This was the worst it got and every day became a little better after that. (4) Dealing with the drains. They are a pain to cart around and contribute to the feeling of being an invalid. (I felt sympathy for the Ood if you watch Doctor Who.) But my drains were gone after about 4 days and then I came home.
Things that helped me through the surgery were: (1) Being fortunate to have a surgeon I trusted. (2) Feeling extremely supported by breast care nurses and other nursing staff and family/friends. (3) A soft cushion to tuck under my arm - comforting and comfortable. (4) The fact that this surgery is on what is (anotomically) quite a peripheral part of my body meant that I could eat and drink normally right after surgery. (Friends who've had abdominable surgery have had a tougher time than me.) (5) Having to massage my nipple to improve the blood drainage (it developed a black scab, but then came good - quite usual I think). This forced me to touch and become refamiliar with my breast at a time when I was still a bit squeamish about the whole thing.
I can see it is a few days since your post now. I hope things are going as well as they can for you. Feel free to ask me anything specific if it would help.
All best wishes.