Very difficult for you.
Can I suggest that Dad considers some counselling. Must be a professional with stroke expertise.
The NHS might have a look waiting list in which case, can he go private ? I had counselling during the first weeks at home and it helped me immensely.
I have also found relax classes very helpful. Havent tried yoga but that might also be a good source of help.
Then perhaps the stroke group. I went a few weeks ago and it was so nice to be with other SS. Like being wrapped in a warm blanket.
Stroke doesn't just get at your limbs, it changes ones brain and often harms internal workings.
Good luck to you both