I havent been in a D/s relationship withsomeone who has been harmed but I have been in two relationships, vanilla for the most part,of people who were abused/hurt in the past. And I wills ay both turned out very poorley and they hurt me a great deal. However. Deep down I wouldnt trade either of them out, and would probably do it again. Well not with them, but -coughs-.
As rago said if it was something serious that needed professional help I would guide her to counseling and not move forward until shes had the help she needs. But I wouldnt abandon her.
If I found someone I cared for, it wouldnt matter their past and I would work with them through any problems they have. Because well, your past makes you who you are today, if someone cant accept your past, welcome it along side of you, then they dont deserve you.