But it scares me so much that for the past 6 months, he might already have had a clear sense of things being "different" at home.
You're being dishonest with yourself if you allow yourself the conceit of "might" in that context. There is absolutely no question whatsoever that he knows something is amiss, and he is probably confused because he knows this, but has no context since his parents are withholding the truth from him. If he is ASD, then this is even more difficult for him because empathy can be an issue for ASD individuals.
The best thing you can do for him, by far, is give him two separate, but healthy, homes to move between. Or, second best, two homes, one of which is healthy (yours), and one of which remains dishonest and dysfunctional (your WW's), that is still better than the third choice of one truly fucked up home that he can't escape from.
Edited later in the day:
Here is another thought, and I must admit that I've read your WW's posts in other forums, which have informed my thoughts. Both of you came here to SI in early/mid March, you asking a lot of the kinds of questions a BH asks in the throes of the first few months after Dday, and her suggesting -- to a forum of strangers to whom she owes nothing -- that she ended the A and went NC. The same fiction she was telling you.
Now, just a few weeks later, you are both back in the wake of the revelation that she has been carrying on with the AP the whole time, lying directly to your face about it.
You said you guys have been together since teenage years, and were first and onlies until her A.
I think that there is a very real question she needs to answer, which is: does she actually want to be married? I frame it that way on purpose. I've no doubt she has love for you. It would be difficult to be together for so long, and build a family, without some level of love. I also have no doubt that she wishes more than anything that there is a path for you to heal, even to the point of having some degree of empathy for your pain.
There isn't enough information in the threads for me to form an observation about whether she has sexual desire for you.
All of those things -- love, empathy, desire -- they are elements of a marriage. But alone they are not enough to sustain a marriage. Lots of people have love affairs, even deeply profound ones, without being married.
Marriage is an express commitment to a high degree of loyalty, fealty, honesty, intimacy, and, most important, monogamy, not just physical monogamy but also emotional monogamy. Your WW's actions smack of a person who does not wish to be bound to those high level promises. I don't mean that she doesn't want to be married to you. I mean, I don't think she wants to be married, period. My gut is that there is a voice inside of her wishing she had sown some wild oats, yearning for the chance to do it now as middle age threatens the end of her youthful vigor and attractiveness.
Her actions really can't be explained any other way, because I don't perceive that she is such a "fuck you" asshole to you, or harbors such deep contempt toward you, that she is simply doing what she is doing because of her low regard for you. Rather, I think her actions are telling you the truth about who she really is and what she really wants to be, which is a single woman.
[This message edited by Butforthegrace at 8:25 PM, March 31st (Tuesday)]