I totally understand your feelings, I am in a very similar place to you emotionally, I have had some very low moments too.
My partner has been in hospital since last September, to begin with he was treated for depression but they are now going down the dementia route. Nobody would listen when I would say could it be some kind of dementia, it’s taken 6-7 years to get this far, I am just sad that nobody would even consider dementia, he is now 73.
I think you just have to accept the bad days, i had days when I just wanted to stay in bed all day and cry, you have to try and make yourself get up and get through the day as best as you can, I felt as though I was grieving for him while he is still here.