Before you spend the time, money, and energy to start down this path, I URGE you to call admissions departments at various med schools, speak to the director of admissions and ask their opinion of your plan. If they say, hey, we welcome non-traditional applicants in their mid-50s, then you've got a shot. If they instead question your motivation and suggest that your possibility of gaining admission is tenuous at best, then perhaps another career in medicine would be a better choice; I always encourage people to follow their dreams, but you may be pursuing a path that is a martyr's quest, with no hope of success. Find out before you try, and remember there are ways other than the full 10 or so years of sci courses + med school + postgrad training to be very involved in direct patient care (PA, etc.).
I think you read the previous posts selectively, without really being interested in answers that didn't match your ideas...
Good luck.