I've resolved to hear him out & will fight like hell to take the high road. Any advice on how to proceed with this meeting, especially if it starts to get contentious.
Just like you said, don't negotiate. That comes later. Just say you have to consult your lawyer about your rights.
But you need to listen to him, acknowledge and validate the crap out of his feelings. Don't bring up saving the marriage. That's pursuing, and it won't be helpful at this time. But if he brings it up, surprise him with the depth of your understanding and willingness to accept responsibility for your part in the deterioration of your marriage. DO NOT CRITICIZE HIM OR MENTION HIS PART. He has to want to get back together before this comes up, or you will just chase him further away.
Whatever he says, DO NOT ARGUE. From his point of view, he's right, and right now, your point of view doesn't matter. You want to make every interaction with you as pleasant as possible, but that doesn't mean you have to let him walk all over you.
Listen and validate. These might be the 180s you are looking for.
Good luck
M:23 T:26 Me:53, Wife: 60 S:18 D:16 filed 7/16 W moved out 4/28/17