Stop being mean to OP. Obviously she is kind. Too helpful for her own good even, but are you being kind by attacking her? As an older sahm who grew up in a large, poor family, I understand helping; its how we survived. She's been alone bc her husband was out of town, kids grown. Its easy to get sucked in by pushy people. Read "wriggle out of babysitting" when dh was home; she has trouble saying "no" and they are pushy.
In the beginning, she was an empty nester with dh gone, occasional sitter for babies, it has snowballed.
She needs specific words that won't create animosity, i.e., "my Dr said that my back, blood pressure, requires my stopping. Your children are getting to be more than his guidelines recommend."
These cfs are neighbors and cfs! There could easily be repercussions if she is rude. Think parking problems, rudeness, etc. They will not be happy she stops.
Not everyone is strong, not all of us are good at confronting situations, i think that OP is my age and not to defend being a "mug" but we were brought up to help family/neighbors. My husband "reprimanded" me today; its built into some of us to help others and even if we know that we are dumb, it is part of us. it is the genetic opposite of being a c.f.? I am grateful for advice bc, unbelievably, I need help turning away people who need help. No good deed goes unpunished....my dh keeps reminding me that it's a new day! " NO HELPING!" As he shakes his head in frustration.
Good luck OP, it was a good run, but they are treating you unfairly and frankly, they are superlative CFs. I can hear the howls now from the rest of this community, but if you can't find the courage, get dh to tell them. My dh would grumble, but he loves me and loves me bc I am kind; and sometimes it means helping me be tough. You can do it! Do not wriggle! Be strong! 