Ganb8te! Awesome! You did great and it sounds like a bit of a breakthrough.
He is sad but feeling hopeless. So how can we get him to have some hope?
I think it is a good idea to text him the book info but see if you can do it in a 180 way. Or just make it really clear that you aren't pursuing/telling him to read it. Maybe say something like "hey here is the name of the book I was telling you about. I found it fascinating!" Not something like "I hope it helps you to ..." or "I think it shows a lot about us .." Not that you would say anything like that but just see how you might be able to show the complete opposite?
What do you think about employing my previous style of ideas now? I think maybe that could give some hope or flip the situation a bit. I don't know if you recall but my suggestions were a bit pursuing but in a confident and friendly way I think.
For example while he is on his trip maybe send him some photos of you on your trip (looking hot of course) or just some photos of gorgeous scenery or amazing food. Not "thinking of you, wish you were here" but "hey, isn't this incredible?!"
Basically keep in touch in a fun, friendly and relaxed way. Build a friendship. Show him that you have a lot in common. Don't bug him with a million messages but just maybe see if you can build a connection in a fun way.
I think it is so funny that you are both dealing with the break up with the same methods - yoga, therapy, meditation. What about connecting with him over yoga, like sending an occasional text about something you accomplished? Make it a competition? Who can conquer crow first? haha
Maybe I am off base but it looks like he is trying to avoid his feelings and wish them away but he can't. You can't rush him through the process but maybe you can try to build a connection so that he can have hope for the future. It seems maybe in your case a friendship would be a good thing. Even if he has OW it doesn't sound like that is the issue.
Well, those are just my few cents of thoughts. Probably worthless.
I hope you are not feeling too down the next day. These emotional conversations can leave me feeling so sad the next day.