It is likely that the snake that was not eating was sick, and gave the illness to the female, who could not handle the illness together with the stress of birthing.
I would not presume that it was your fault.
I would suggest that you soak the viv and all of the dishes and other equipment in bleach water... one ounce of bleach per quart of water... for 20 minutes, before getting another snake. After that, check some of the threads in the husbandry section as well as the caresheets in the Articles section of this forum, to make sure you were not making some sort of mistake.
Then, armed with that education, go ahead and get another garter or two, preferably from one of our forum members. That way you are less likely to bring in a disease from the outdoors.
Good luck!
