LGF - I'm certain your children won't reject you. They will make sense of everything gradually in their own way and come to an understanding that they are happy with.
Maybe one approach could be that the medicine to make you better will make your hair fall out, and when your hair falls out it means the medicine is working well. (as I say mine were much older so if I'm talking nonsense just ignore
)
Figgy well done on talking to your DS, and is great he wants to help you choose a scarf. Actually any little thing family members can do that lets them feel helpful in a situation where they will feel very helpless, is a good thing IMO.
My DS spent a lot of time drawing up charts for my temperature, my pills etc. - not strictly necessary but it made him feel he was doing something 
MAS I will PM you the bits and bobs I jotted down re the book - I meant to do it earlier, this bug has addled my brain
. I'm not sure they will be of any great use, as mine were grow up. It's just jottings, not perfect prose 
Love to all. thinking of everyone starting chemo soon 