I just caught up on your story and see that you got a lot of great feedback. It sounds like you have really stepped up and are a wonderful father to your kids, and you are handling the whole situation with such immense grace and dedication. I wish the very best for you and your children. When you eventually start to date again, I can tell from your posts that any woman would be lucky to meet you!
I have a lot of experience with divorced families, and just had a quick comment to some of what you wrote:
If STBX asks you for school info (or other info about the kids), it would be wise to answer - even if it is just to direct her to the website where she can find the answers herself. Not answering at all can put you in hot water with a judge. One of the very important factors they look at for custody decisions (and potential later changes in custody!) is which parent puts effort into facilitating a good relationship between the children and the other parent. Just wanted to give you a head's up.
From what I'm reading about your STBX, she doesn't sound like a good caretaker *at all*, but I wouldn't give her grounds to complain about lack of responsiveness on your part.
M 16 yrs, WH62, P54 3 adult blended kids EA 11/13, BD1 6/14 PA fall 14, BD2 2/15 Piecing 2015, BD3 12/15 Separated 4/16 WH moved OW in 5/16 Divorced 6/15/17
I wish the very best for you and your children. When you eventually start to date again, I can tell from your posts that any woman would be lucky to meet you! 
