I am only a few weeks from my first D-day.
The choices are not just R or D. There is a third option, "Not Divorcing", and this is what I recommend for you for now.
It is widely acknowledged that it takes 2 to R.
My WW will barely talk about the A. When I have brought it up, only a handful of times, she shuts down, gets angry, and starts playing the blame game.
This is not a WW who is ready to be a full and rational M partner. She needs to understand why she had her A (other than the reasons blaming you), and have taken steps to repair her issues before she can fully participate as a M partner to try to R the M.
Is there anything I can do to move in that direction?
Notify the OMís BS if there is one and you have not already done so. Then I suggest you set out the boundaries, the requirements that you have for her in order for you to "Not Divorce" at this time. Common boundaries soon after dday are NC with AP, transparency with access to email, cell phones, schedule accountability, etc. Her attending IC to help figure out why she had her A may be another boundary or requirement. Having her read Not Just Friends by Glass and Sexual Detours by Hines and discussing them with you may be more. Her and you being tested for STDs is another important early step.
When your WW has demonstrated trustworthiness in NC, transparency, etc and has figured out and owned her Whys for the A, then she may be ready to work with you on R.
While you are Not Divorcing her, this is a good time to rediscover yourself. Cultivate a social network of friends, revisit hobbies or activities you may have given up when you M. Consider IC for yourself to help work through your post dday feelings and thoughts. Talk with an attorney, not to file, but to understand the legal implications for you in your state. Start setting aside some money that only you have access to, and work on budgeting so if D is the final answer you will have the funds to do so.
Best Wishes and keep posting and reading.