Kuma nailed it on the head. Your family is just thinking what is "Best for you" not know what the best really is. They are just generalizing a life that you might live that is easy if both people were healthy etc etc.

But they dont understand how you 2 have a common interest. Like a couple with a hobby, this is something you both share, understand and fight through together. So if this is what makes you happy and you can sustain a life with the situation you are in. Then there is no need to worry about what others say. They probably have the best intentions but are just unaware of the true situation!