How is taking control or YOUR finances and protecting your credit (not having bills paid late) moving closer to a D? It's ironic that you feel separating finances would be the final straw yet the fact that you haven't lived together in some time AND she is with other men don't seem final to you.
It's a control issue with you. As long as you and your W still have something joint then you have a shred of something shared with her.
And you are correct, you should have never called her about the book for your daughter/how to fill out the form and payment. How hard could the form be to fill out? A while back my H e-mailed me asking me where he should go to get the car inspected, lol. Men that can't figure out simple tasks *are* annoying.
This is why many of us feel you come across as needy. If you wanted your W and daughter to work out the book issue why did you get on the phone with her at all?