I’m not noble. I’ve declared my undying enmity of all that is good and beautiful at least twice today (excepting Mrs. Rhymer, of course). But we needn’t be tacky.
I’m finding I have to stay out of political threads since the election, because I don’t want to say things I’ll end up regretting down the road. There’s a few people I wouldn’t be able to hold off gloating mightily and nastily to. (Anyone seen Rand Rover in the last couple of days? I didn’t think so.) I’m not noble, but I’m trying to be.
Let her have it. By your own addmission, four days later she will rationalize a reason to forgive you!
…
Or God will have interceeded on your behalf, whichever. 
I think Miss Manners excepts being rude to insane right-wing relatives with computers (if she doesn’t, she should). Blast your sister-in-law any way you feel fit - I’d barrage her with stories and pictures of the noble President Elect Barack Hussein Obama. All in the interest of enlightening her and sharing the good word, of course.
I’d send her Obama’s a link new website: http://www.change.gov/
She can send him an email and tell him what she thinks!
This is awesome. Send her an evite!
…or this one…