I pretty much agree with Upset. I watched W lie repeatedly for more than a year. It was ridiculous and even now, I'm struggling with dealing with it. You could watch her do something or catch her dead to rights and she'd lie about it. WAS's are so adamant in their denial you start doubting your own eyes and ears.
I don't think I'll ever forget, but I'm trying to forgive. I keep telling myself that something "broke" inside her for a while. Not really a good description, but it helps me not to dwell on it.
I think the books will tell you that they do need to own up and take responsibility for their actions but I'm not really sure she has, or ever will. I'm actually afraid of what it might do to her if she ever realizes how much damage she caused. She was a good person before all this started, and she's a good person now. But she was definitely off the deep end there for quite some time.
I really don't want her to go there again. But can I accept what happened and get over it? I'm still not sure. For the most part, I try not to think about it too much. That gets easier over time.