How do I convince dad its time to have someone assist with his AM care?

I provide care for both parents..Dad pretty much alert, yet slow with aging/parkinsons..bathing is a real problem as I cannot get him out of the tub..yet he insists he can do it himself..I have back problems, Mom attemps to assist , yet is to small and frail..one day they both will fall. He writes checks to his grandchildren without a second thought..but to assist me in assisting him - no way...I hate butting heads with him yet another argument is about to come. I was advised to apply for medicaid as they have funds to provide home care, but the application was filled with many real personal information...why is that..and i'm not sure I want them to invade into our lives at this particular time...please advise as I'm about to loose it...i'm really tired and beginning to feel it all!