Going dim is fine. I understand how hard it is to go completely dark when kids are in the mix, but you can achieve a good level of dimness. I did that with great effect and only communicated about kids and finances at the time. I think it's good that you're keeping a level of cordiality in front of the kids. Keep it out of their sight as much as possible.
The place where I had a very hard time, and failed most of the time, was keeping things cordial and having an indifferent attitude. I think this balance is key and hard to achieve, but one can with practice. It took me a while to get there and I still wish I had done it better.
About the email / phone thing, don't ruminate on it too much. Those are small things and they will find fault where they want to find fault. It's the overall macro approach that makes the difference with being consistent with DB strategies.
develop boundaries is probably one of the main things. If her making snide or angry comments bothers you, set a boundary for yourself to disengage and then follow through with action. Yeh, she'll be more pissed, but you'll command more respect in the end.
The main thing I can say is this - try and live your life as fully as possible without worrying too much about her. the more you can move towards detachment and building a life that you want, the better you will be in the end no matter what happens.
