Good question. I believe in girl code. I sent an email to OW informing her of the devastation they're A caused our family and ended the email with, "women aren't suppose to do that to each other, we're suppose to support one another."
I feel so strongly about it that before i even knew about my WH's A's I refused to help out for a school fundraiser (I volunteer for almost everything.) When my friends asked me why, I explained that I didn't like the woman coordinating the event because she use to be an OW but they both left their BS's to marry each other and I'm not helping her. Sure, the bigger picture is to raise funds for the school but that would have happened whether I volunteered or not.