Hello :)
I can see from what you have described about your living situation that it must be stressful. Though my first advice would be for your father to discuss therapy, I feel that may be too ideal and he is not the one reaching out here.
My two cents to you are that we are culturally bent towards mistaking self care for selfishness. As a working adult, you must take care of your own needs first. Anything that impacts your mental health to the extent that you lose concentration, needs to be dealt with. Being obedient, as desirable as it's made to seem in our society, can also sometimes mean we put ourselves in unhealthy situations just for the comfort of our elders. You can take care of yourself, and in doing so you will find the energy to be of more help to both your parents. That would be respectful too.
I hope you take care of yourself :)
Next Steps
You could perhaps seek counselling yourself to help manage your feelings and thoughts around your father. That should help you focus on your work, and generally impact your mental health positively.
Health Tips
Since this is a sensitive matter, considering your father's health conditions, I would recommend seeking support from trustworthy close ones before your making decisions.