That helper instinct is going to be hard to rid yourself of; it is human nature. And yes, you need a break from him and from the situation. I realize it is hard to back up, but it might be a 180 for you, maybe ask if he has another way to travel or get someone to ride with?
He keeps talking about her, because he wants to justify what he has done. You'll notice he keeps saying she made me feel this or that. Baloney. She did not make him feel anything; he did.
I noticed there were no words in there about how he feels about her? I noticed he wants to be pursued, again so he can rationalize his behavior.
Impossible, just keep yourself neutral and listen and when he's gone, take a breather. Relax. Try and do not obsess or try to figure out what he is doing, because you have NO idea.
Strange feeling here today. Not detached yet. But moving away from the hurt. Read, if you get a chance, the letter I wrote myself today.