NewMama - I'm EXHAUSTED for you just reading your thread! I used to have that kind of patience with kids - taught beginning ballet for years to 5 & 6 year olds - but no more. Hope they move THE BOY for you - it's not fair to you, him, or the other kids to have to spend so much time with him.
That's nice that your stbxh took off work to help to stay with your sick son. The last time my WH did that was in 1999, and he gave me hell about it. In fact, when I told WH that I had a problem yesterday, that I needed to take S 7 to karate from 5-6, go to a parent meeting at 6:30 and pick up D 13 from dance at 7 - and I couldn't do it all - he said, "Yep, that's a problem." Then he went to his regular Tuesday night riding lesson without a second thought.
At least your stbx is ensuring a future with his son. Mine will be old and gray and wondering why his kids never call...