Faith, you do not have to apologize anymore. It is not a matter of you trying to say something that will fix her or the R. Time has to be a big part of her therapy, and that is with the expectation that she has stopped her EA.
If she is still lying about her A, it is either b/c she's going deeper undercover and thinks she can make you believe it was just your imagination.....or else she's in some kind of denial (which seems crazy, but the mind can do crazy things).
I think at this point, you need to focus on yourself GAL. Don't push her about her feelings toward anything. Don't ignore her or act cold, but treat her as if she was just a kid sister or somebody. The least thing can make her feel that you are smothering her.
If you still love her, then don't give up yet. Getting a life and focusing on the things you like does not mean you've given up.
I know it's confusing for you. I know it's awful. Try to be strong and take care of "you".
It is not about what you feel should work in your M. It is about doing the work that gets the right results. Do what works!