S8 has apparently forgotten (so too his mother) of the difficulty he had had when riding the bus in prior years. Everyone seems to be forgetting how our AS son was taken advantage of by the older students -- a situation that W had used as an excuse to take him off the bus in the first place.
And W had used the excuse that S4 needed preschool 5-days per week (instead of just two) in order to be able to learn better with his peers. Seems that reasoning too has been reversed.
I think your W really makes decisions based on what will be best for her and not your sons, and in that, she is consistent.
To me button-pushing is the kind of comments your W likes to make to you which seem an obvious attempt to make you react, the comments like you think you're god or you killed the marriage or there you go again or things like that. I don't see the school issue as button-pushing, but a serious issue that needs to be dealt with. Those other kind of comments I think you should just ignore or leave when she starts making them, I agree with the schooling you will have to deal with that. When you've discussed them attending 3 schools in less than a year, she doesn't see that as a problem? Have you thought about family C or something? maybe that would be good b/c helping your W to realize you both need input on that and how harmful it is, etc. I don't think a good C would agree with that kind of parenting. Karen