No Babe, you aren't going crazy. It is very hurtful to see STBX under circumstance of ill child. It is familiar. Family. And he bashed it up. You don't get over this all at once. You just needed to let off a little steam. Sounds healthy.
STBX gallant behavior just pisses me off. It's guilt & I don't appreciate small gifts of platitude & good behavior out of guilt. It makes me cry too. I don't know if it's the same for you. My husband has been attentive, best conversationalist etc AFTER he made a fool of himself lusting after his ex wife. I want to stab him in the eye. Please don't do that. I won't either. I'm just blowing off steam.
Temporary setback. If you think of something STBX can do, tell him. Otherwise, crickets to him.
I think you should also take time to feel good that he offered to help you heal. It's best to stay detached until you get further down the road though. Get use to this. You can even tell him, "let me get back to you, it might be a few months"
You WILL get you back again. You are already noticing it is better. You will notice more & more. You will notice your laughter, true laughter, coming back etc. This changes us but doesn't have to ruin us.