Divorced and moving out.....still hopeful

[NewB3]

So tonight she calls me to ask me if I recall that I am watching him tomorrow. I said yes I will be there early. She then tells me how she's had a rough weekend and since it was nice whether, she had plans to take him to the zoo. He was very excited last week about that. When the time came Saturday he did not want to change out of his PJs. He is done that all weekend. Ask him if he wants to go to the park he gets excited about it but will not change out of his PJs and so he says, let's just stay home. She said so all weekend I had no choice but to stay in the house. We've done nothing. And the weekends over. My thoughts here are if we were together I could've stayed home you could've gone out and vice versa. However she chose to go this alone, so she has to deal with that not me.
I didn't told her that he seemed quite sad last week and maybe that's the problem and that he had said some things. She said he hadn't said anything to her. Well I told her what he said about wanting his family back. She said he came in this morning when he woke up he screamed her name ran into her room knocked over a piece of furniture and began hitting her in the face. I explained to her that he may be having emotions that he doesn't know how to deal with. He's angry and sad. I've seen that myself although he doesn't get me. She said well I seem to be catching the brunt of it.
Although I didn't say it, surely anyone can see, he is mad at her for breaking up the family. He senses it somehow. I've never told him it's mommy's fault. Any suggestions on this?