Don't do it. Even if you have your facebook profile locked up tightly, once you add her as a friend she will have some level of access to your friends and family and not all of them will most likely have their privacy settings set to allow to friends only (many people leave it set to "friends of friends" so she could conceivably see things that other people post, and comment on them.)
And you can't depend totally on privacy settings and blocking. I was in a private, closed group. Those posts do not show up to anyone except the people who are in the group. Your friends do not see them, though they can see that you are in that group.
Somehow, some way, a person on my restricted list on Facebook saw a post I had made and confronted me about it. The restricted list is basically a list of people who are not allowed to see anything that you post on Facebook, but can still be on your friends list. That is supposed to be impossible. And no, we did not have any mutual contacts in that group...it is a highly specialized group.
Facebook isn't that dependable. They also change privacy settings from time to time and even they are advising people of this right now with the total rollout of Graph Search.