Well what are you hoping to get out of going to grad school?
What I mean by that is, school is part of the "real world" - so if you are there for career advancement, remember just like there are student's like this woman, so too are there colleagues like her. How would you handle this at work? You'd probably do your best work while documenting, documenting, documenting, right? So you do the same thing now. If you are in a group project with her, you CYA while doing your best for the project and then you present your work, and the documentation of how the workload was divided, to your
boss teacher and let the chips fall where they may. Learning to work with and deal with slackers is just as valuable a skill as academic knowledge you will pick up in school.
If you are in grad school not for career advancement, but simply for the love of learning and knowledge, then just push forward yourself and let her figure out she's a slacker that no one wants to carry the load for.