I hope you've gotten some comfort from the posts.
I would only add two things -- one is to make sure and tell Dr. Brackman himself of your concerns, your desire to continue nursing, etc. My impression from posts here is that he's a wonderful guy; we tend to idolize doctors so much that we forget they are actually interested in our lives, our children, how your surgery will affect your particular life -- and they're willing to help your particular situation.
The other is to please, please, make sure YOU get enough rest after your surgery. Experience with relatives has 'proven' to me that rest is critical to recuperation.
As many have said, children are resistant -- they'll do fine. If it's any solace, my mother had a radical mastectomy in 1952 when I was three years old (I'm 59 now, and my mother was a 40+ year breast cancer survivor when she died in the '90s), and although I think I've had some "abandonment" issues because of that experience (none of which I remember), I'M FINE -- I like myself, I'm having a good life, it definitely didn't "scar" me forever.
Do keep us posted, acknowledge your fears, know that it'll take time to recover, but know that you'll be OK and your kids will be OK.
Dana