bm, I would look at this a little differently. These kinds of incidents are actually good things. WAWs/WWs are notorious for thinking that splitting up the MR is the best things since sliced bread. That if they could just get rid of this lunk of a H out of their lives their lives would be all rainbows and unicorns. That the only thing holding them back is this crushing feeling of being stuck in an unhappy marriage with an awful H that has no way or idea how to make them happy.
It usually takes reality to snap them out of it. What I see here, and the reason she reacted so viciously to it, is reality hitting her between the eyes. When S wants his toys, wants them now, and wants to remain with you because that's where they are, the reality is in that this thing isn't going to be as easy as she had hoped. Though she was lashing out at you, she was really lashing out at the reality of a family that is currently split up. A reality she doesn't want to face.
WWs especially want what they want NOW, and they don't want to hear anything that says that the decision they are making or made is wrong in anyway. When reality proves that the decision wasn't the best they sometimes react poorly to that reality.
So don't take any of it personally. I think you handled it well. My only suggestion would be to go back to not being so quick to immediately respond to texts and calls.WWs are also known to be "nice" to get their LBH reattached. When you go NC, and go to being slow or not responding at all, they'll often times turn on the charm to reestablish that control. And they'll even use possible R to reestablish that control. If you read the other sitches here you will see that is an universal dynamic with WW.
The natural reaction for the LBH is to go back to being responsive. Don't be. When she picks up S, and 5 minutes later is calling you....let it go to VM. If she starts texting you shortly after she would be getting home, don't be so quick to respond. Do not stop DBing just because she has been a little nicer recently. Remember, detach when they react to it and detach when they don't!
M(53), W(54),D(19) M-23, T-25 Bomb Drop - Dec.23, 2017 Ring and Piecing since March 2018