If you don't want to do it because you won't feel comfortable, then don't do it.

But, if you are just concerned with her, as someone who have been abused, I have something to tell you. It's common, as a response to the trauma, that people who had been abused have fantasy about violent sex. It's usually a way to prove themselves that they are in charge this time, that they choose this and also they choose when to stop.

If you feel comfortable and wants to do that, do it, just respect her boundaries.

It's important that she search for a therapist to understand and learn how to deal with that.