Baby, I feel for you.
My mother is 41 and if my father were still alive he would be 78.
I have always lived with my grandparents and great parents.
When I was about 12.. We took in my great-grandmother.
She was stage four pancreatic cancer. She didn't tell anyone until treatment was too risky and too far gone unfortunately.
When she finally moved in with us because we begged her to, she didn't want help. She wanted to be on her own, doing her gardening and being the lady she was brought up to be.
In the end.. She asked us to just put her in the hospice.
It broke her heart and ours but we knew it was the right thing to do.
She fought a good fight and I'm sure your father is fighting the good fight. She actually died a day later after we moved her into the hospice. She wasn't alone. She was being taken care of and we knew in our heart that it was the best we could do for her. It is life.
If you need more help and if finances allow, maybe think about getting a nurse to help out when you just can't take the responsibility anymore. It is alright to feel overwhelmed. It is a hard thing, believe me. I know.
Do not feel guilty that you can't handle it physically or emotionally anymore. You have done your best and you know that in your heart, you have.
If you didn't.. you wouldn't be asking this question.
I would recommend just sitting with him in normal conversation and bringing up the idea of possibly getting a part-time nurse or be put in a better home where he can get the care he needs. It isn't unreasonable to ask when you just can't possibly do everything even though you wish you could.
I wish you the best, I really do. I know you can get through this. You are strong and you know it.