2) Yes - your W is all over the place but that is not something new. KUDOS to you for keeping it together!!! You didn't let her punch your buttons!!! You are diffusing her aggressive behavior by reacting calming and assuredly. AND - others noticed. You deserve a large brownie sundae for that! Way to go.
3) You are looking at your situation and at your kids with a world of hurt - so totally understandable. But, what if you took a moment to look at it from your W view. Take out the part that she left you and broke up your family... now look closer. We live in an evolving world but its still hard I'm sure at times for the world to recognize a child may have 2 parents of the same sex. Your W simply wanted recognized as a parent too. Even in divorced settings of heterosexual couples there are issues where one spouse can feel cut out from the children given that exact scenario. Could you have just gone back to admin and gotten W a wristband???
I can tell you that even the walk away spouse can carry anger and resentment because of the failed M. My H was really angry... and he got even angrier when he noticed that I was capable of changes and making things different. His interpretation is that I could have done it all along and didn't want to because he wasn't important... doing it now was like pouring salt in a wound. AND, I've had those exact same words from a dear male friend in a similar circumstance with his W.
So hold your head high and keep moving forward. W notices. BUT, don't forget to step outside and look at it from W view point --- even if its not your own... even if you feel that it was her choice to walk out and with someone else... you don't know her thought process... maybe in her mind she tried and tried but felt your ability to make that connection was too little too late... her behavior now could simply be she is seeing long term change coming about.
I would spend my time biting my tongue and being the better person for the benefit of my kids. Even after her behavior if she suggested you walk out together I would have done it for my kids. Your son notices that you are not reacting emotionally... wonderful!!! Now show them you can make a united front for the sake of those little ones. They are more important than the world of hurt W has thrown at you. When your kids are grown they will know the love and devotion it took to get there. The best advice I can give in drama filled custody issues is that you don't always need to be right.
You are stronger than you were months ago... you go girl!