i agree with sati and DiablosLittleOne comments hun.. if you let her find out on her own and you have already left then where will the support be..?? At least right now you could direct her to this site and even after you leave she will find comfort here ...

If you don't know how to approach bringing her here .. you coudl always gt her near a compute and bring the site up telling her it is a place you frequent all the time and the friends you have ..and what the site is about letting her know you are into this sort of thing to .. so there won't be any more beating around the bush and she knows it is ok to open up to you .. just as she has over the lesbian issue...

just my thoughts good luck

hugs
snow