Model on Relationship as a care giver

Background is that FIL is on chemotherapy. While he actively chose to do this, now he is refusing to eat or drink, or keep up his physical activity or even take his chemo meds. Unless all of his food/drink/meds are brought to him and he is persuaded by me or MIL to take it he is not taking them.
C- FIL’s care during Chemo
T- HE needs to take charge and follow through with his choice of doing this.
F- Frustration
A- Spend hours at each meal/medication time persuading him to eat/drink
R- I am exhausted physically and mentally. He still hasnt taken charge.

T- I show up in a way that I choose to in his care, the rest is up to him.
F- Clarity(in our respective roles)
A- Make his meals/beverages- hand those to him per schedule, request him to take, trust him and move on to my next task.
R- Each of us do what we can do and let the other person be/do who the are.
The challenge here is that in the 2nd model I do feel abandonment parallelly- that if I dont push him we are abandoning him- but I also know that if he doesn’t take charge, this journey is going to be very difficult- we have to be ok with seeing another human suffer in front of our own eyes. Help please. I need some peace!!