Sorry to hear that.
If the people she failed to help (and you helped as a result) are still around, I'd talk to them and see if they would be willing to sign off on that fact.
Also, if you know people that weren't helped or neglected when they needed it, see if you can get their consent to cooperate also.
It's may be after the fact at this point, but I'd think sending a letter signed by others that have been neglected or ignored by this person would have some affect on her job security..
Also, if you intend to do something to her in the form of a beatdown or other revenge method, I would wait a little while until she thinks the incident is in the past.. Then do something. She won't expect it then, and it will be that much more effective.
Again, I'm sorry to hear about your situation. Unforunately, the world is filled with its fair share of people like your manager.. Generally, it's best to avoid them when at all possible.
Take care, and good luck.