You're not responsible for her growth. You're responsible for knowing the truth about your life.
This statement is so spot on read it again.
Then take a step back. It seems you want to R really really badly - What are your internal reasons for this other than you love her.
Are you afraid to D? Are you afraid to be alone? share the kids? What are the real reasons you have not pulled the D trigger up to this point.
I agree that her actions and your statements about them are incongruous. True remorse and rebuilding has to be built on a foundation of absolute truths. That said, I want to give an example of my own personal path in R.
My H was somewhat conflict avoidant and grew up in a home where his mom was forced to lie to have her own $$ and some control in her life, so he grew up seeing lies as being acceptable to "keep the peace" so to speak.
However.... it is really important for people like this to understand that telling the truth doesn't cause WWIII, and as adults we can have uncomfortable discussions and reach resolutions which is WAY better than lying and covering those lies.
When Real R started for us and I knew I had the full truth he had hurt me multiple times in the early days with broken NC and lying about it, and like you I had a 6th sense of it, and knew every single time it happened and I asked and he lied. Initially it was some limerance, and fear of being totally alone should I find my backbone and toss him out. That said when I did find my voice, my strength and my backbone, I did just that. I told him to get out the last time he broke NC w/ her. I had put a logger on the computer, and knew it the second it occurred. I returned home (from work at 8am), and handed him my rings and said I'm done being an option, and a doormat. You have 15 minutes to gather some belongings and get out. I will contact your Mom about when you can see the kids later today.
That was our real turning point. He knew I was done. He knew I would no longer tolerate another lie about his A. He completely fell apart. After consideration I decided he had one more chance. He absolutely had to send another NC email. Block her on his phone etc. He did. He also had to promise me (for what it was worth) that he would tell me without me asking everysingle time she reached out to him, no matter the method. My end of that bargain was to not fall apart, or get angry, but to have a civil discussion about it.
My second requirement was no more lies of any kind, no white lies, no minimizations, no half truths, no whopper lies. NONE. If I saw that he wasn't being truthful instead of letting it slide I was to hold him accountable and call him out on it. He too was to hold me accountable and call me out everytime I was behaving in a codependent way. We had a Bullshit rule. When we saw the unhealthy behavior in the other, we were allowed to call them out on it, discuss it, and resolve it, without the other losing their shit. It worked for us.
We became very real, and very authentic. It probably came across as quite raw to others, but it worked for us. We cut out the bullshit and were authentic, and that is when we really started to rebuild and get healthy.
So my point is this. You have somewhat backed yourself into a corner, but it is resolveable at this point. I would sit her down, and have the D documents in your hand and tell her you absolutely know there is something she hasn't shared. Now is the time to come clean and if she doesn't you will file, if she does then you can absolutely start to work toward a real rebuilding of your relationship. But make sure your reasons for wanting to rebuild are going to be enough for you to be happy and fulfilled in the future, if not then skip the drama and just file.