I'm not exactly sure that carrying an unborn child makes the sitch any different than a couple with kids of any age still at home. Plain fact is WAS has left not just you, but a FAMILY - just that you can't see the little one yet. My W was so keen to leave she could just pack up and leave the 4 of us, not just me.
What you are both dealing with is a serious case of Cake Eating. H wants to have the good things about having a kid, the newborn smell, caring for someone so helpless, just the "gorgeousness" of a new baby, while still being able to just "opt out" whenever they want to to be with OW.
As for wanting to be a parent in a meaningful way but have no commitment, that's just a load of crap. They can't see straight thru the fog of the A.
P, you have to protect yourself and bub. Centerlink have a vast amount of resources dedicated to supporting families and especially new mothers in failing R's. It's their fastest growing area. Also make sure you get in contact with the Child Support Agency as soon as bub is born. They will take care of getting financial support for the new one from H (although it is harder if H is outside the country).
So to my stumbling block, what exactly is your definition of co-parenting (you too NM) ? Is is shared care of kids together ie 2 parents together under same roof or is it drop off/pick up.
If it's the first then make sure it's something you can deal with without going mental. Being together yet apart from H will just get your hopes up because of the proximity you will find yourselves in.
If it's the latter then I'd have reservations, especially with a first child, about a new father being responsible enough to have sole care of a newborn. Not that guys are bad dads, just it doesn't come as naturally to us, and then there's the feeding etc.
H: 44 W: 42 Married: 23 years Bomb: 16/07/2009 PA Confirmed: 16/01/2010 Over it & working on ME: Feb'ish 2010