Hi Jim, glad you had a nice time with your kids, and sorry it wasn't the easiest handover. I'm sure they will get much easier - it's still early days after your S, and things are still pretty raw.
"she just simply wont engage on any level and is avoiding any small talk to avoid me getting hopes up" - I think this is mindreading....who knows why your W is behaving this way? It may be not to get your hopes up, it may be a range of other reasons...as V. would say - no doubt all will unravel in time.
As Mozza suggests, it may be worth mixing it up a bit with your behaviour in handovers. If you have tried being chatty and pleasant with a brick wall in response - maybe try a quieter, but still neutral/pleasant approach and see how that goes. Try not asking how she is, or did she have a good weekend?
I too wouldn't broach the SIL letter any further....and I love the hornets nest analogy....My Mum always used to say, "if I tell your brother the stove is hot, he'll put his hand on just to see! Here's the thing though Jim - No good will come of it! You've seen your W's demeanour now. She's never in a month of Sundays going to admit her sister went OTT with the letter. I would leave it well alone, unless she raises it. And if she does, you can maybe just say - Oh that? Not to worry - no need to talk about it.
T x
T 13 M 7 Me 48 H 46 SS 15 BD 7.14 PA D final 5.16 (H filed)
We receive & we lose, and must try to achieve gratitude & embrace with whole hearts whatever of life that remains after the losses - Dubus