Its hard and I know it. Detaching with love is a hard concept. If your brother law needs help, you should share that with your W.
When it comes to communicating with your W, think about it like this, if its something she can live without knowing them don't tell her. But if you know it's something she has to know them tell her.
You shouldn't be calling her up and saying, "guess what I did today". But you can call her amd say I talked to your brother he's seems to be not doing so well. If you truly couldn't pick up him not doing so well, then send a text to W saying I talked to your brother today.
Now, stop playing your W games. She asked you what date, and you chose. Next time, she gives you options and you chose and she then takes away that option you chose, you simply state, "you gave me two options I chose the option that works best for me, I will be there on that date I chose, if you are there or not". She will test you and she won't show for your date, but you won't show for hers either. Then she will be forced to have to work with you once she realize you are no longer part of her game.
M:37 W:37 T:11 M:10 S17, S13, S10, S4 BD:06/28/17 OM confirmed 07/20/17 Recon the M 10/29/17 Working hard:2gether
Onward and forward
This process is not a sprint it's a marathon! Patience, Patience, Patience.