Really hoping for some impartial advice here if you don't mind reading.
Background: FIL developed dementia which grew (slowly) worse. MIL wasn't fully coping. Asked DH/me/the kids to move in to help. House was big enough for us all so we said yes, figuring it was temporary. To cut a long story short: FIL got A LOT worse, I became a part-time carer to someone who couldn't be left on his own. The rest of the time was spent looking after my young children and fitting in freelance work. Eventually we hired an actual carer because of double incontinence and severe mobility issues. FIL sadly passed away after about two years.
Now: Between MIL not wanting us to move and the kids being settled in school, we're still here with her. It isn't a dire situation by any means. We have almost entirely separate living areas, bathrooms, kitchens, due to the house setup. In lieu of rent, DH pays her bills, council tax, utilities, and for the bulk of food shopping. Just for the record, there are no cultural expectations. DH is white British and although I'm not from this country myself, I come from a place that's culturally similar.
The problem is, MIL's expectations of care have crept upward so that I am becoming resentful. I cook for her every night. I walk her dog once a day. Cleaning duties of communal areas are left entirely to me. She's run off two professional cleaners through abrasiveness so God knows what her personal quarters are like. This has been going on for the past three-ish years and it feels like having a horrible teenager around. She has her good moments from time to time but even my youngest child isn't all that keen to spend time with her because of MIL's prickly attitude.
Her dog is borderline child-aggressive and I utterly resent having to walk him. There is no garden here so he has to go out. DH had a hard conversation with her when FIL was terminally ill, telling her that she needed to either rehome the dog or take more responsibility. After throwing an almighty tantrum, she chose the latter but in actuality I do 50% of the animal's care. Now it's years down the line and he's getting to be elderly and it will be impossible to rehome him, not to mention he isn't trustworthy around children (my 8 year old knows what his triggers are FYI, and is never unsupervised with him).
Basically I have reached the end of my tether with MIL's increasing needs and the way she expects to retain a high standard of living without putting much effort or help in. I feel like she makes decisions rashly and then expects us to step in and handle the aftermath.
Am I being mean to just... back off? To stop walking the dog every night for her? I do worry sometimes that she's a bit frail. But the thing is, as soon as I step in and take over a responsibility, she assumes I'll keep doing so. Then I'll see her swanning off to meet a friend and think, why did I just help her when she clearly has the energy to do it herself?? Why am I left picking up the pieces? Several nights ago she spilled a drink on the carpet and didn't bother to even put a paper towel over it. This is not an isolated event - nor is it out of character for her since she did that kind of thing ten years ago. This is part physical (being elderly) and part just not giving a stuff.
We do have a potential solution in the works but I need to cope in the interim. Someone mentioned a rock method in one of the threads but I can't find it now.
I think I just need a bit of perspective on this - I don't want to be mean and I hate feeling like I have been. But I also feel like I just don't want talk to her these days because 80% of what she says are demands or complaints. I am becoming snippy with her which makes things uncomfortable for everyone, and is not great for my marriage either.
So this has turned into more of a rant than intended. I'll end here. Happy for anyone to say look, you ARE being a bit mean here, give your head a wobble. Just please, if you do, explain your reasoning so that I can try to shift my attitude and cope accordingly!