jakbrown,
firstly, dont feel guilty. I am seriously considering this for my dd, or hopefully will be able to pay a carer for the 6 week holiday as this one was a COMPLETE NIGHTMARE, honestly.
secondly, my friend is a foster carer but she has special needs children on a full time basis for quite q while (sometimes 6 months, sometimes less) She has been used as 'emergency' foster care where she will have the child for a couple of days up to a few weeks. She is lovely, doesnt judge and i would be happy for her to have my dd needs be.
thirdly, I think you are being very realistic about the future, your fears may be unfounded, but if not you have the foundations there to make your life easier. It is bloody hard work looking after a severly disabled child/adult. you deserve a bloody break for your own sanity.
Fourthly, (hope i am on the right number here! ) your friend....I would say give her time for now, but I have lost (or forgotten) alot of friends because they just dont understand how my life is with my daughter. I have 'friends' judge me, even saying i do not 'do enough' with dd. i do evrything I p[ossibly can for her, she is my daughter. At the end of the day you have a choice whether you stay friends or not. She may just need to get used to things, or just doesnt understand how much you have to do for dd. Hopefully your friend was having an off day
HTH and i havent just waffled for ages!