It is good she talked with you. It was good that you were empithetic while she was complaining. Just remember to listen and not try to "fix things". There is a thread in newcomers about "a failure to communicate" and I posted toward the end all the things I have learned about commincation. It was what my W and I have always struggled with.
I think you need to give her space and time, just like I have done with my W. You have to let go of your fears and take a "leap of faith" to trust her judgements. If she sees you genuinely care and trust her she will be more comfortable to open up to you.
You also have to let your fear of her MF go. You have no control over it and if you give her any indication you don't trust her with him (even if its him you don't trust) she will back away. Women need to know thier men trust them. Trust me I have learned the hard way.
I have read through some of your post, but I think you need to set some goals for yourself. Some just for you, and some that she will notice. It may help to type them out here and get some input on them. You have to lovingly detach yourself from the sitch so the pain won't be so bad.
I have come to learn this just recently, and I find that I can be happy alone and when I am not with my W. Once you get to this place she will notice and will want to be a part of your life. Even if it doesn't work out, you have to be happy with yourself. You have to love yourself before you can love anyone else.
Start some goals and lets get to work.
Take care.
God Bless You,
Reuben
Cautiously hopeful and keeping the Momentum