Have you considered hospice for your mother? Hospitals, nursing homes and specialty care centers (like dialysis centers) have social workers who can help you find hospice that can come to her home and take care of her at the same rate as you, and some might even be covered by Medicare (just depends on her coverage, what’s wrong, etc).

Can you afford a nanny? With the extra time you’d have if you had one, maybe you could add a couple more hours on at work (hear me out) to have some alone time in the evening and make back the money. Gives you time away from the family and if you have an office job, usually people are gone by 5 or 6 and you could relax and do some stretches while working for yourself.

Also, sounds like your wife needs some Major therapy. Sometimes employers have an EAP that will set you up with a number of free counseling sessions. Might be worth a peruse if you have insurance/an employer that offers that.