Just checking in on your thread. Looks like I will likely be over here soon as well.
On your issue with STBXW making negative comments to the kids, you are handling this well. Do not stoop to her level. Not once.
My parents D'd and pretty much had a terrible M as far back as I can remember. My mother had all of us kids convinced my dad was at fault. She repeatedly said bad things about him after the D. My dad never made a negative comment about her. Never.
Eventually, we figured out the truth. My mom had a lot of mental issues (still does) and made my dad's life (before and after the D) a living he!!. And, we all have a great relationship with our dad, but very few of us talk to my mother now.
Hang in there. Be the better person. It will all come out in the end. How do you want to be perceived at that point?
