My feeling is that all this time at work is not entirely work, some of it is contacting OM. And I think OM is cooling. Perhaps he feels that the fun of talking to her is not worth the fear that you will be telling his wife what's going on. As she gets rejected by him, she goes into a funk and withdraws from family life. And I think she is testing to see if she can re-interest you in a sexual relationship.
As for ballet, yes, tell her the little one is crying because she wants Mom to take her to ballet. Rabbit's plan, above, sounds good. It is not pursuing to keep her informed of things the kids tell you. Why doesn't the little one tell Mommy herself? I can't see how asking a mother to be involved with her children is pursuing.
