If it helps at all, it seems to me that your guy is exhibiting the classic signs of mlc - which can include this ridiculous idea that they have met 'the one'. Out of the blue and after just a short time, they 'know' they were meant for each other.
Look back and you can probably see elements of this in your own experience with him. You were the one, too. And you have the years on the board to prove it.
Mlc is truly like a mental illness in my experience. You have to view it like this to cope with what he is doing. Patently his behaviour is just mad.
People will say that you are better off without him, but this doesn't help much. You still want the man you knew.
Unfortunately he doesn't exist at the moment. He may not in the future either. Those are the sad, hard facts of this terrible condition.
Given that, you know what your options are. Really only to keep going, living your life in the best way possible without him as part of it. And keeping some small hope in your heart that he works through his crisis and realises what he's done.
It will take some time, so in the meanwhile you have to build a new life for yourself from the ground up. Sounds terrifying, but it also represents a big opportunity, if you can grasp it.
So sorry for the pain. I know what you are going through (I suspect my X has done something similar in the last couple of weeks, but just doesn't have the guts to tell me and our kids.)
