Getting difficult

We are getting down to the last stages I think. Chai's back legs are flaccid, she has urinary and fecal incontinence, she won't drink her water very often - she has developed a fear of it, perhaps because of dementia. She just got over a UTI and bladder stones, but with being so dehydrated she could get them again. I think she's still happy to be alive. But I am weary and sad and not as enthusiastic about caring for her as I used to be. I'm tired of the house smelling like pee. I guess I'm reaching, or have reached my limits, but I don't think she's reached hers and I couldn't put her down until she's ready, or it would feel like killing, not mercy. So, it's a hard time.