I know, I agree. I'm sick to my stomach knowing this will be done today, most likely. And even more sick to my stomach that I was once one of those parents, who didn't want to listen to the other side, and I did this to my boy, and made my friends feel like I do right now.

BIL will regret this forever.
SIL is the type of person to completely close up in an argument, instead of discussing things rationally. So the arguments have gone basically like this: BIL-- I really don't want to circumcize our son. SIL-- I DON'T want to talk about it. We're doing it. End of story. (door slams shut)
Don't get me wrong -- I care deeply about them both. But she is hard to argue with, because she refuses to even talk to you.