There are some men conditioned to apologize to the W.........in order to continue on. And there are some women who throw fits, give the silent treatment, withhold sex, etc., as a means "to condition" the H. Half the time he has no clue as to what he apologizes for, but he thinks that is his script to follow. With that said, why did you apologize for talking to your MIL, especially since it was done before you and W agreed not to tell anyone? In the future, don't do it, just as way of making peace. Apologize if you have done something wrong,but otherwise, I say the WW will continue blaming everything on you.....whether it's your faul or not. Your MIL is the one who called her out about the A, but your W took it out on you.
You called her out about getting mad over the ice cream thing. Excellent job! Now that you see you did not fall down dead, and in fact had a positive and immediate response from her.......continue going forward.
I tend to be suspicious of any WW who "appears" to clean up her act immediately following the H's confrontation about her A. Usually, she will take the A to a more secretive level.....being sure to not to be caught this time around. I am not saying your WW is not genuine, I am just saying what I have seen in the majority of these same type stories.
Has the MC given you and WW a plan for transparency? Have you actually seen any message she sent OM saying it is over? Has the MC discussed repentance with your WW, or has been more of a "forgive & forget" and now move forward? I am just trying to get a better idea of what's being presented to her.
I hope she is authentic in the effort you see in her. I really do. I realize you want to see progress, and I certainly don't blame for feeling that way. Just try to be emotionally prepared if she backslides. If she truly told OM the A was over, then she the addiction will be pulling at her and the temptation will be tough.
As for the sex issue, you are pushing. I know you can't think like a woman and you see having sex as sealing the deal. It is your way of making progress within the MR. The fact she is even willing is much more than most WW's I have read about. Unless she is high drive, she probably cannot feel connected until she is over OM. In the meantime, you are building the whole intimate thing being the fixer until the pressure is too much. Some of the guys will probably comment, but I'll bet it is not uncommon at all in this type of stitch. Let go of expectations, and give both of you time.
I also hope you will keep us updated, even if it's just to let us know you have not left us.
It is not about what you feel should work in your M. It is about doing the work that gets the right results. Do what works!