Generally, a person in crisis will "choose" one child over the others to be best friends with. It is usually the one that will not question/challenge them on what they are doing.
As for W's appearance, she's depressed and isn't sleeping and possibly not eating healthy foods. Many of them go to fast food places or eat a lot of junk food, i.e., like they did as kids. It's quick and they don't have to deal w/cooking and cleaning up.
Yes, your W is hurting deeply. She is mourning the death of her old self. Her focus is on her and she knows that deep down you and the kids are hurting...but right now...she's focused on easing her pain any way that she can. The guilt she feels may keep her from coming around as much...and that's another cause for not sleeping well.
While she is floating around in La La Land, please try to keep the focus on you and your kids. I know it's difficult to do, but you are now the "main" parent and the kids need the stability that you provide. Keep the focus on your finances too.
Good luck today.
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.
