I recommend figuring out your requirements for R and seeing if your WS will sign on. If they won't, perhaps they can come up with something else that will meet your requirements, but if you can't negotiate something truly acceptable to both of you, great - you can go directly to D. Otherwise, you can monitor them for 3-6 months and commit to R for yourself if they are (is?) consistent in meeting your requirements.
The requirements need to be observable and measurable. That way it's easy to monitor progress and make adjustments as you go along.
Common requirements include:
NC - no contact with ap; if ap initiates contact, report to BS and together decide how to respond
Transparency - BS has passwords to e-mail, voice-mail, phones, etc.; WS keeps BS informed of whereabouts, activities, and companions at virtually all times
Honesty - WS answers BS's questions when they're asked, although sometimes a break is necessary, sometimes an answer is best deferred to MC session, etc., no more lies.
IC for WS - to change the thoughts and feelings that supported the A, with signed release that enables C to talk with BS about WS's goals and progress (so the BS can make sure WS's IC isn't being lied to).
IC for BS - for support - and for resolving any internal issue that comes up
MC - to help communications between the partners. Be careful to avoid MCs who don't deal with the A first. An MC who starts off trying to identify systemic problems probably won't help. You need someone who will help resolve the trauma before going into systemic problems.
Some (Most?) people have individual requirements - my W had to arrange dates for us on a weekly basis and must initiate sex sometimes. What do you want from your W?
And R is a joint endeavor - if one of you hides objections to the other's requirements, you sabotage R. And you have to see your WS as a human being of worth equal to your own to make R work. You don't have to see your WS as a human being whose worth is equal to your own, but you sure can't R, except with an equal.
Sometimes requirements need to be renegotiated as time goes on. A number of things I wanted at the beginning faded in importance. I agreed to wear a ring at my W's request. I hate wearing a ring; since I didn't cheat without the ring, I asked my W to withdraw her request.