jks, I've gone through something similar with my MIL, SILs and we have been family for over 30 years. I was angry and hurt and fell into victim mode. But wise people advised me that I could make a choice here. The choice I made was to not mindread their motives. This is an awkward, painful situation for everyone. If I wanted to reach out to them, I could.
I call or see my MIL occasionally.
I wrote my SILs a note, saying something like "I know this is difficult for all of us. This is between H and me and I have no ill feelings toward you and hope we can remain friends." One SIL wrote back, the other didn't and neither has reached out to me since. I haven't reached out to them either.
I choose not to be affected by this. I like to think that if I were in their shoes, I would respond differently but I don't know that. It's really not worth wasting time on. Their response or non-response doesn't change who I am.
I agree with Vero, when people want to tell you that stuff, politely (or not) remind then that you won't talk about your inlaws with them.
You'll get there jks, it's just not easy.
Me 57/H 58 M36 S 2.5yrs R 12/13
Let me give up the need to know why things happen as they do. I will never know and constant wondering is constant suffering. Caroline Myss