Dont tell her. Let her ask. If she asks then answer her honestly and if she doesnt then dont bother with the issue. This way you wont step on her toes afterall you are only answering her qs.
One other thing. Does she ask you a lot of things about herself and are you the kind of guy that gives an answer because its nice rather than the truth? If so i would stay clear of the issue anyway because she might simply be asking you these things in order to get a soft answer back that justifies her doing it. Not saying that this is the case but just be careful if it is because you will end up falling out.
Sincerely,
Westside.