Dog aggression problem?

I have a 2 year old mixed breed (german shepard, pittbull, black lab, blue heeler) female dog who is in heat, going on the 4th week. She is normally very gentle but during this heat (I have 2 other dogs, a female and male) has been aggressive, its always towards the other female, not the male, these are dogs that have always got along. The aggression usually happens when Im putting the female in heat into her crate, or, if she is allowed near the other female while the other female is in her own crate (I put them in crates when I leave the house for awhile.) The female in heat is much smaller than the female but we've had 2 instances where she has attacked our other female. The first time it happened I was right there and tryed to pull the one in heat away (the aggressor) and I got bit. We have talked with our vet and do plan on having her spayed after this heat, but, I have actually become afraid of her, and feel as if Im walking on eggshells around the house, Im also afraid for my other female dog. Im just wanting to get opinions on this if you think this may now have become a habit for her, acting aggressively, or if it may be remedied by getting spayed? Thank you for your time.