It is a good sign that your WW is beginning to own her actions and her A. It took my FWW nearly a year to get to that point.
I know its different for different people but how long did it take?
About a year after dday, FWW started IC in earnest to work on her issues. She had FOO issues and borderline personality traits to work through. She has been working on this for 2.5 years now and is much better, but it is a a work in progress. For many of her issues there is no "cure", only learning new and healthier behaviors and thought patterns to replace the earlier unhealthy ones.
In times of stress she will revert back to the old behaviors and thought patterns. I am told this is common. The behaviors learned and internalized as a child never fully go away. When we are stressed or become lax over time we tend to settle back into those behaviors. In my FWW's case she has 50 years of learning and acting these no longer helpful behaviors, it will take more than a few years to excise them.
I want to be supportive but what was the best way a BS can support you through IC. I feel like its individual thing.
I will not claim mine was the best way, but t was my way and seems to have worked. I detached. Not a full 180, but we became much more like friends than H & W for nearly two years. I made IC available, I did (more than) my fair share of household chores, I tolerated no sex (<6x a year), I tried to be supportive. I also protected my boundaries and expressed my needs.
During this time I also worked on finances and budgeting to begin to accumulate some buffer in savings if D ended up being the outcome. I continued working on me, some IC, exercising, re-focusing on my career, hobbies, establishing social friends.
You are right, it is an individual thing. FWW has had to face many ugly truths that she had been denying to herself. I know she did not enjoy her IC, and often was quiet and withdrawn for a day or two after a session. This is part of why I detached during this period. It would have been too difficult and unhealthy to enmesh myself into FWW’s emotional struggles that I could not control.