You did nothing wrong. If she was put outside and got pregnant by a local tomcat he could have passed something to her kittens, or these kittens were just premature and she is aware that something is dreadfully wrong. Don't get upset that she started to get rid of one, in her mind she is trying to keep her family save and get rid of anything that brings predators to her nest. It doesn't matter that she is safe inside your home, she still is driven by instinct.
Please get her spayed after this is over for her.
And do not let her outside, losing all these kittens will automatically throw her into a heat cycle and if she gets out, she will get pregnant again.
You said these kittens have no hair? If they have no hair they are way to early to come on teh scene, and unless you are really skilled at stimulating, and tube feeding premature kittens, it is doubtful they will survive. I'm sorry, I just don't sugarcoat things-