It didn't take long. SIL's email began with, "I wanted you to know why I returned your gift..." and proceeded to list some of our many transgressions. It concluded with, "if you want to have a relationship with me, you know where I am." It was ugly, manipulative, and classic SIL. It contained language designed to draw a wedge between DH and I and other members of the extended family.
There was a time when an email like this would have tied me up in knots, rendered me sleepless, and ruined my holiday. I am so grateful that DH and I are beyond that now.
There is a lot of power that comes from not caring.
Good for you! Your SIL could be my sister, and I found there's a lot more power in not caring enough to respond or acknowledge her accusations than to get drawn into the crazy (thank you eHell!!!). I wish I could say I don't understand why people like this attempt to stir up so much drama, but you said it yourself -- SIL used to be able to get you all tied up in knots, and she's betting on still being able to do so. I've found it's best just not to read the crazy e-mails (because they *would* annoy me). DF still has to learn not to read the crazy e-mails; he thinks he's being impolite by ignoring his future family member; it has been very hard to explain to him that responding will give her what she wants and teach her that this unacceptable method of trying to get to ME (by overstepping boundaries and e-mailing HIM to complain about me) is an effective way of forcing communication. If he doesn't read them and doesn't respond, then she'll eventually wear out and go have her snit fit elsewhere -- same with your SIL. If you don't respond, she doesn't win (and, I have found from the past twenty years of dealing with crazies like this, that the most satisfying and most powerful way of responding to them is to not respond at all -- drives them nuts while also leaving you at peace).
What a shame that she would be so ugly about a gift! I'm sorry this happened to you and your DH.