Got to say I agree in a few ways w/the other posters.
His response is very telling as to how lost he is. He knows what he needs to do, but doesn't know how to do it. Time is what he needs.
I also love Lisa's point that you've found something he doesn't like - moving forward w/out him - so you need to keep doing it. Keep making plans and invite him, but do them whether he comes or not. It is obvious this eats at him, so keep it up!
I too would say don't respond at all for a while...maybe even a few days. He's expecting your reply to come right away. Don't send it. Think long and hard about what you'd like to say first. If he gets it in a week, that would be fine too.
