He will find help if he wants it.
You are not that help.
Detach means...detach. I have an ex who tried that a few times, calling to chat. I didn't let him get any conversation going at all. As soon as I knew it was him I said, "I don't have anything to say." That usually makes for a very short conversation.
On the "amends" thing? You don't have to listen to that. If he was in true Recovery, he would have run this by a sponsor and his sponsor would have never told him to call you at 1AM and do this.
This guy is trying to reel you back in. Don't take the bait. You don't owe him anything and there are plenty of people in AA who will listen to his "poor me" stories; and they will set him straight on his BS. Don't believe him when he gives you a sob story about how you're his only friend and how much he cares.
He's an ex for a reason.