I don't know how to answer that--what does 60-80% look like?
Your initial question sounds rhetorical. Is it? You sort of answer it here, but I wanted to make sure:
I need to see enough that it makes me want to recommit to her for the rest of my life. I don't yet even know how I'll know what I'm looking for. It feels more binary to me--her defensiveness and lack of empathy is what I've been narrowed in on for a long time. I feel very tuned in and appreciative when she's displaying empathy for me now and very alarmed when she's not.
This is a start to what you should reasonably expect. What you need to ascertain is the minimum you will accept in your relationship with her. This is where your boundaries should be both established as well as rigidly enforced.
You asked the question. What does 60-80% look like? Maybe a lot like you are seeing now: empathy at times, but selfishness, entitlement, and passive-aggressive behavior at times as well. Envision yourself two years out from the affair, when everything is no longer as raw. Can you accept what you are beginning to see now for the long term? This aspect of your healing needs to be clearly understood by you. If it isn't, what is acceptable to you? Only you can answer that question. And if you are having difficulty answering that question, think of it this way: would you accept being treated a certain way were you to start a new relationship with someone? If the answer is no, then it should be no for your WW as well. As you are seeing, there is no way this is binary. The only way it becomes binary is either through perfection or the opposite, neither of which occurs in the real world.
I think some part of you is being optimistically opportunistic in this situation in that you now are insisting on trying to make a broken relationship what it should have been from the beginning. That is understandable, and hopeful, but not necessarily realistic. I would encourage you to strive for the relationship you want, but more importantly, clearly lay out the minimum you are willing to accept. Make sure she understands that if she fails to meet those minimums, there will be consequences.
For example, when my wife has PMS, which is a large struggle for her hormonally month-in and month-out, she has a tendency to snap at me over nothing. When that happens, I use a script:
"Would you be okay with me talking to you that way?"
"I am not okay with you talking to me that way."
"When you talk to me in that manner, it causes me to feel like you don't really care about me."
Those are all boundary and/or feeling statements. I then follow it with consequences:
"I am going to leave the house for a couple of hours and do something for myself. Please do not call or text unless it is an apology."
This does two things. One, she wants me around when she has PMS. But she does not get what she wants when she treats me poorly. Two, it builds self esteem and self love because I am refusing to tolerate the intolerable. The root of codependency is a lack of self love, so every opportunity to enforce a boundary is an opportunity to build self love as well.
One more thing about codependency. Right now, I think you see yourself as a supplement to your WW's IC. YOU ARE NOT ANOTHER THERAPIST FOR HER. In this healing, there is a great saying I learned from a poster on another site: Keep your eyes on your own paper. It is your job to enforce boundaries with your WW. It is her job to respect your boundaries. It is not your job to communicate why it is a boundary, nor why she broke it. This is where codependents run into problems. As soon as the inevitable "why" questions gets asked, it becomes a debate. Then the codependent starts to get their boundaries curtailed. Do not engage in "why" discussions. Tell her she can respect the boundaries or not, but there is no debate. If it is not important enough to be rigidly enforced without debate, then maybe it isn't important enough to be a boundary.
This is where we bring it back around to your initial question. If, six months from now, she still lacks the ability to respect your boundaries, or she herself decides on boundaries that don't work for you...which is what she effectively tried to do with saying no more discussions about affair sex...you have your answer as to whether or not you can remain married to her because what she wants and what you want are simply not compatible. Then you will have to have the courage of your convictions and let her go.
The biggest thing that codependents struggle with are boundaries. Ask me how I know... If you figure this out, you will be well on your way out of codependency.