This is really a myth. What is "killing the middle class" is that our expectations for health care far exceed our ability to pay for it.
O.K., how about the way we pay for health care is damaging competitiveness and depressing wages and discouraging entrepreneurism, and discouraging legal hires, and causing the middle class to be dissatisfied with decent wages when they have no health benefits. It will soon be close to 20% of GDP. Too much.