You've already gotten some really good advice. Just take your time, and only open up discussion if she opens the door...simply starting discussion on an already known hard topic will only shatter her trust in you. Be creative about going about getting her to talk; her fears are valid, but it's getting her to admit that they are there, and that she wants to get over them.
As far as helping her gain confidence in the horse, the thing I like to do is use a horse I myself trust, and get her doing everything and anything on the ground, to build confidence and trust from there up. Then start putting her on a horse on a lungeline, and start from there, as well...Again, you have to be creative, and she has to be showing that she wants to make a change, otherwise, at this point in time, you will just be doing a bunch of talking...it won't get through. It's hard to evaluate where she's really at, unless a person is there to witness it, so unfortunately, all we can give are suggestions...they may or may not work. The best thing you can do is just continue being a friend to her...showing her how you handle your horses, and how much you trust each other because of the way you choose to handle them.
"The ideal horseman has the courage of a lion, the patience of a saint, and the hands of a woman..."