Wendy's the winner!
So here's what I did:
I told her to shut up and to drop it and let me be pissed. She said, "I have dropped it, you're the one freaking out" (or something, I was kinda enraged).
At that point I told her to get the hell out of my house. I totally wanted her to leave. It sounded like a good idea to me.
But then my mother flipped out. She freaked the frack out, and I ended up having to apologize to my sister for telling her to leave the house (it took about 10 deep breaths), and then I started to tell her that although I was sorry, that -- and then she cut me off and said, "Shut your fing mouth. I don't even want to look at you."
So I went back to the kitchen to resume cooking the goddamn asparagus, and every time I opened my mouth my mother hissed, "Shut up." Or, "Don't you say a word."
So I locked myself in my room for an hour and played my stero LOUD.
It felt good. Like I was sixteen again, in all the ways that sucks and rocks.
I do sort of regret telling her to get out of the house, but not because I wanted her to stay. I still wish she'd taken her happy ass out the front door, and I am angry with myself for being scolded into groveling, and then with letting my sister talk even more shit to me. But her leaving probably would have ruined the day for everyone else, and that wouldn't have been nice. In retrospect I should have taken her out to the garage and laid into her, instead of in the kitchen in front of everyone.
I didn't speak to her the rest of the night, and sadly, she and her husband stayed until nine or so. I haven't spoken to her since.
I don't really care that much if my sister and I have a good relationship. If we weren't related, we wouldn't be friends. She's done some seriously craptastic things to me in the past, and at least for another few years, I'm done trying very hard.
So. I don't want to talk to her, I don't want to see her, and I don't want her to think I'm actually sorry for telling her to get out of my house. We'll see how it goes.
Advice? And even if you want to be like my mom and scold and shame me, yeah, um, it won't work.