Oh, this is a long one! Thanks in advance for reading. I don't want to drip feed.
I love my DM very much. In some ways, we are friends more than mum and daughter. However, she can occasionally demonstrate difficult behaviours: she can be manipulative, controlling, interfering, gets terribly 'hurt feelings' when she's not happy about something, etc. A lot of her happiness is centred around me and my DCs: she gets very down when she hasn't seen us for a week or so, is quite entitled in terms of visits.
Also relevant info is that she's always been young for her age, she's fit and healthy (always exercised, good diet, little alcoholic, etc). She's now mid-70s. For info, she is happily married to DSF and has a wide circle of friends, so not lonely.
She has been through a very difficult time recently as, in the summer, she was diagnosed with breast cancer. She has had chemo, now beginning radiotherapy and is clear, thank goodness.
Her cancer treatment has taken a lot out of her. She's beginning to look and act older than she was. It also seems to have affected her mentally; she's not as 'on the ball' as she was, sometimes she doesn't seem to hear or understand new info, doesn't always follow conversations. I don't have concerns about dementia: I'm sure it's not that, she's just a bit 'flaky' (or flakier than she was 😁). An example of her not being 'on the ball' (there are numerous): at her house this morning, she made coffees and set the just-boiled kettle down at the edge of the worktop, just as DD(5) was reaching up to the worktop. I bounded across the kitchen to move the kettle to the back of the worktop and checked her reaction - there was none! She didn't seem to notice.
Before her illness, she helped me once or twice per week with childcare. I really appreciated her help, although we didn't need it, as such. Latterly, I wasn't always entirely happy as she insisted on driving the children to her house (she will never look after them at our home) or to various locations, taking them out for lunch, shopping, etc.
Her driving had begun to concern us, slightly at first. In fact, around the time of her diagnosis, DH and I discussed stopping her driving them around any more (she'd had an accident that didn't cause injury but, from the way she describes it, was completely her fault but she doesn't accept that at all). This caused me massive stress as I knew it would be a huge fight and she'd take it as a terrible insult.
So, understandably, she hasn't been helping us with childcare since her diagnosis and that's been fine. We see her for visits, around once per week, although she obviously doesn't see the kids as much as she did.
She's now hinting, very heavily about things going back to 'normal', wanting to take the kids shopping or to the cinema, etc. This would involve her collecting them in the car, driving there and them dropping them off at home. Due to the kettle incident (and others), I'm not confident of leaving them solely in her care at all, even without the car.
No matter how we say it, this will hurt her terribly. I will be 'ridiculous', 'unreasonable', 'cruel', etc. She classes my DCs as hers, as I am 'hers' and they are an extension of me.
How do we say it in a way that hurts her as little as possible and doesn't cause a huge family fall-out?