I know that he's putting off doing the timeline because he figures I've done my own timeline & that's good enough.
Gently said, and I'm challenging your thinking patterns here,
"I know". You don't know that. Remember how we stop looking for an explanation when we find the first one that suits us, that satisfies us, _our_ thinking? Let's change that to, "I think".
"he's putting off doing the timeline because" and this is an explanation that satisfies your question of "why is he putting off making a timeline?" There are other explanations, though. Like he could be saying, "I don't want to do it." Why? Well, "it is hard and thinking about the A makes me feel badly." Why? "because assholes have A's and I'm not an asshole." Why not?
Or, "I don't think that she needs one." Why? "She wrote one for herself." Why can't you do this thing that she told you that she wanted? "I don't respect her enough to do something that is hard for me." Why?
More accurately, in my opinion, is something like this:
"I think that he's not writing a timeline because he knows that I've written one and he doesns't want to do it."
But this could also be true:
"I don't know why he isn't writing a timeline. He hasn't told me." And this one drops all of the self-created reasons that he isn't doing anything. By letting go of assumptions about why he's doing something you open yourself up to thinking about it more, to really digging deeper into his reasons, why they are selfish, and why he is selfish. Realizing that your needs are secondary to his when he fucks up is a valuable lesson in your value to him.
Again, my own opinion:
He screws another woman. He emotionally destroys you. Then he sits around and reads a few books that you buy and listens when you rave and rant and says, "oh, hey, that's me!" and agrees a few times with you about what an asshole he is. Oh, and the books describe him, too.
Then he goes about laughing with the kids, doesn't really do anything hard at all, and I'm betting (I have no knowledge, here) that pretty soon he's going to start acting shocked and hurt about you being shocked and hurt.
Regret: he's sorry that he got caught. Remorse: he's fully realized how he hurt you and what you are feeling and puts his wants on the back burner to try to help you.
Which is the one that you're seeing and how long will you put up with it?
That's a very good question, by the way. It does take a WS a while to get to remorse. And the whole time that they're getting there the BS is getting stronger and more ready to leave their ass in the dirt.