Hi Jenny,
Sorry I cant really help with the "kind" of recon you're having as I had tissue expanders and then silicone implant exchange, but either way, sucky that we have to be here! But great that we have such a great place to come to for support!
My daughter was just 5 when I was diagnosed and went through all my surgeries (2 years from beginning to end).
Try and be as honest as you can, but at that age, they dont necessarily need to know the intracacies of the op. I'd just let them know they'll need to be "gentle" with you, tell them you have some "sores and bruises" but as long as you have some rest and do as the Dr tells you, that you'll feel better soon. Let them know that maybe you cant actually hop IN the bath with them, but you can still sit with them while they are in there.
This whole journey needs some "rules" hey? I think most of us just wing it and do the best we can. Kids are pretty resiliant and as long as you are matter or fact and you're not too secretive, they'll love their Mummy either way! :-)
Hope this helps a little bit, good luck tomorrow Jenny, let us know how you go. Try and get a good nights sleep and enjoy being waited on in the hospital! Dont hurry home, it'll all be there when you do. :-)
Sam x