Muddle, at some point it simply has to stop mattering how she feels about something or what she wants. You can't keep living THIS life the way you are.
Yes, if you take action "A" or fail to take action "B" then she may do "C" but who gives a damn. At some point she CAN'T have it all her way, which BTW is destroying your marriage.
I know you have to be tired, at your wit's end over all this. I am and I am not even there. She SCREAMED at you for not doing something she said she was going to do? I bet if you HAD picked up the snacks she would have screamed about THAT too because SHE wanted to pick them!
Over in piecing Ali has talked about her H's verbal abuse in terms that made it seem like she was trying to either figure it out or cope with it. It seemed like the fact that her H's behavior was TOTALLY unacceptable no matter what the circumstances were wasn't a prevalent theme.
I think your W is out of line and when she does those "out-of-line" things, and no I don't mean having an affair, I mean treating you with total disdain and lack of respect, I think it's perfectly ok to just go on about your day until she decides to approach you differently.
Don't be an a$$, even if she accuses you of being one, you know the difference. Just live and do it with love and honesty, especially towards yourself. If she wants to join you, then fine, if not, well she will learn what it's like to be without you.
GH
P.S. Sorry if this was less than optimistic or positive. I am just tired of the way she treats you Muddle. Take me with a grain of salt today.