If you have chicken wire and scrap wood, you could make a framed door for now.
Maybe the cat was pregnant, are you sure it was a she? Are tom cats more aggressive?
Oh no!
Chickens aren't good at seeing at night. That isn't a good thing that she wasn't scared of you. Do you have a no-kill animal shelter near you that you could catch her? It would be good to get her out of the area especially if she is the only cat that has attacked your flock.