Your kids are too "busy" to offer any assistance to you when you've had a health scare? Do they live locally? You took care of them, and raised them when they needed the help, now it's their turn to help you. I simply can not fathom how a family can be so dysfunctional in today's society.
Family was the most important part of people's lives until recently, but not so much any more. The most important things in people's lives now is themselves, they come first. It's becoming a generational thing, and I'd put the blame on social media. Everyone's face is glued to a device of some kind during every waking hour, and it's turning the world into a population of narcissists.
I'm sorry that you're experiencing what's happening to you, and I wish that your kids would realize how important you are while you're still here.