My dad is in his 70s but capable of cooking for himself/ driving to shops.
so stop doing it.
When my nana passed (16 years ago) my aunts (there are no males) all did everything for my grandad, who was more than Capable of doing it himself.
Quite frankly, they didn't help him. He had nothing to do. He started deteriorating mentally and physically as all he was doing was sitting in a chair waiting for people to do stuff for him. And even then it wasn't enough.
My (male cousin) offered to cut his lawn on a Tuesday. But he didn't arrive early enough (9am) so grandad phones his mum calling him all sorts. It made no difference to grandad wether it was done at 9am or 10am.
And yes he became even more religious than he was before. I think mainly because he didn't have anything to do. He also became very judgmental of everyone.
Quite honestly, if you are doing things for your dad, that he can do himself, I don't see why your brothers should help. It's your choice. He doesn't need caring for.
Once grandad got bad enough to actually need care and developed dementia, I also helped care for him. But I wasn't going to to do it while it was a choice for them.
You need to take a step back. I am sorry you are having such a bad time of it. But you need to take a step back for your own physical & mental health.