Family conference time
all sibling, mum together. Get your mum to say what she wants. She may struggle at first, but keep probing till you understand her “ vision”. Then discuss options with all siblings together on how to get as close to that as possible. That way she can’t play you off against one another. Or dump funding solution on one of you.
also, being a carer for someone with mental illness (let’s include dementia in that, but my experience was 20 years with ex with psychosis ), completely changes the dynamic of a marriage. Instead of equal partners with you own autonomy you are forced into a “ parent “ role to your spouses “child”. You aren’t just caring for them physically, but having to do all their executive thinking skills ( planning, anticipation, problem solving etc…things we all do in minuscule ways everyday without realising). It is relentless, overwhelming. Add to that the person who’s got dementia or psychosis doesn’t know they’re ill, doesn’t know or acknowledge what spouse is doing to support them and often can actually be accusing them of controlling them. Intimacy dissapears, not sex but any physical affection, as the ill person withdraws more and more into their mind and effectively becomes selfish, well self absorbed, and lacking empathy for their carer spouse. There are some studies to show that physical attraction is turned off when someone is pushed into a carer role in an intimate relationship, hypothesis is something genetically to prevent incest with children we care for.
your mother is struggling emotionally probably . She’s likely grieving and on the grief pathway but stuck as your dad hasn’t died or left her. She likely to be berating herself with her lack of patience, tolerance and possibly growing resentment at you father. That’s all normal but horrendous for her and family witnessing her perhaps becoming cold and uncaring towards your father. In younger marriages, sadly, the statistics are frightening- 90% of marriages fail and 1 in 2 careers become mentally unwell themselves .
your mother will probably not want to admit fully to what she’s really thinking or feeling as it doesn’t meet with the “ sickness and health, better or worse” vows she took . If she is moaning at you, it won’t cover half of the emotions she really feels, the pain, loneliness, guilt, frustration, despair.
you have to get her to see sense and admit she cannot, no one can, take care of your dad on her own. She must be able to sleep properly as that alone won’t help her mental health or patience. That’s the priority- you must get you all together to discuss and agree a way forward. As others have said the shear mental stress of being thrust into this situation will possibly to kill her before your dad 😢