Hi Barry. Sorry you are having such a hard time I am very far from a vet but a few things you raise in your post make me think you are too close to your own sitch to see the wood for the trees. Firstly and most importantly is the kids are all important. Their whole world is upside down and you need to be like a rock for them. Listen to them , validate their feelings and STFU about the unfairness to you. They are trying to get through this and you need to support them
Your W might be getting on with her life with no regard to you. She might not. You have no way of knowing. My W can be laughing and joking one day and talking suicde the next ! People change their minds all the time , why can't you W
Whatever brought your W to her choices didn't happen over night and it's unlikely that she will decide to come back overnight either.
It's so hard but you are where you now. All you can do is control you and improve yourself Let your actions show your W the difference not your words
Re in laws that's really tough but at the end of the day there are her family and again nothing you can do.
Post often and hopefully some vets will chime in with their advice and guidance
Please keep reminding yourself that all you can control yourself. Be the very best you that you can be and either way you will come out of this experience a better person.