Ah, another AIBU by stealth. You mentioned nothing about her kids being at school full-time - what you did say was that "she offered her home so she didn't have to arrange a babysitter and it made it easier for her". From that, one could have assumed that she could have had any number of children running her ragged to the point where she could not get enough time to socialize outside of home with her friends. Or that's how I would have chosen to view it.
And I still think YWereNBU till you made it a point that she didn't work (like that should have anything to do with it). I don't work (not at the moment anyway as on maternity leave) and I can categorically say that I DO NOT have oodles of spare time on my hands. What I do have is an extraordinarily demanding 5mo DS who is feeding every 2/3 hours (whom we shall nickname Velcro-Baby), a 3 bedroom house and garden to keep tidy, never-ending housework, and a short temper (courtesy of the fact that the longest spell of sleep I've had since DS was born is 2.5 hours!). The only spare time I get to myself is on the weekend when I can dump DS on hand over DS to his father and, even then, not for that long. And before you ask, most of my mumsnetting is done via an iPhone on the bloody loo, seeing as that's the best spare time I get (sorry if TMI , but 'tis true )
You and your friend are different. What you may find easy, she may not. I definitely don't agree with the wording of her email or the way in which she conveyed the message but, frankly, if you are not happy to put yourself out for others independent of them doing the same for you, then don't - no one is making you.
Attitude = opinion = view, but frankly, your post at 22:48 shows attitude in the negative sense of the word. I'm sure you were referring particularly to your friend, but you seem to think that SAHMs must be draped over their embroidered chaise-longues with a vodka martini all day. (PS - Wherever that reality is, I definitely want in on it! )