Specsy, I agree with those who said just relax and give Bella a bit of time to recover from the shock of this. What happened was probably quite traumatic to her, as it was to you. In time you will both calm down. Don't dwell on it.
It sounds like the leash and the way she focuses on other dogs just builds into frustration and rage. I don't know how much work you've put into attention training, but if you can start taking her for walks again, just work on getting her to focus purely on you. Start back at square one.
If you pass yards with dogs in them on your walk, and you know those dogs are out there, start asking for her attention maybe 20 feet from the yard (maybe more, maybe less, you know your dog better than I do) and if you get it, turn around and start walking back the way you came. Praise her, give her a toy, give her food. Do an about-face and start walking back towards that yard with the dog, but get a bit closer this time if her attention is still on you. When her attention is breaking or you see her starting to reach her threshold and a hissy fit is incoming, stop what you're doing, get her attention on you, put her in a happy mood, go back to your last successful attempt and repeat that a few times. Build up slowly to the presence of another dog. That's the only thing that really worked with my dog, just slowly building up her tolerance to the presence of other dogs while we're out on walks, and increasing her threshold to the point where she will only snap/bite if the other dog is right next to her and touching her.
Your goal should be to walk by another dog and have Bella in a heel position with her eyes on you. When you can do this near your home, start taking her new places and trying it. As long as you are one step ahead of her and have her attention, she can't react violently. As I'm sure you know, you have to be a proactive handler when you have a reactive dog.
With a dog who displays violent tendencies towards other dogs, I have no idea how to kindle safe, healthy, normal interactions with other dogs.
My own dog is completely socially inept, and the best I've achieved with her is encouraging her to pretend dogs don't exist as long as they leave her alone, and protecting her from the rude ones who don't take snarly faces as a hint to back off.
Edited to add: I don't know about doing bite work with a dog like Bella. Her problem is with other dogs, her nervousness is with other dogs, and I am not sure how bitework would do a thing to help her insecurity with other dogs. There are plenty of things you can do to boost her confidence without doing bitework.