Caring For Grandfather With many Medical Issues.. Am I in the Wrong?

Im caring for my grandfather who has alzeihmers(earlier stages) He is also not able to walk or do any occupational duties for himself. I moved in a few months ago cause the Doctors were no longer going to allow him in the care of my grandmother alone.. Thats why i came here to basically help and to prevent possibly a nursing home/isted living. Now when i came back i sat the family down and explained what i was there for. Reason being is i come from a family where my grandfather owns a business. I explained that im strictly here to care for my grandfather and i am not here for the business. Also we made an agreement on $450 a week 4 24-7 care. Now remind you I have my own place and I left my life to ist the family but what has happened is im constantly being asked to work this business.. Im drained emotionaly and physically enough doing the care giving let alone taking on a business.. Am I wrong for this? Am i asking to much money? Just some feed back.. Am i unreasonable.