Orbinator: welcome!
This guy is your Ex right? going to stay that way? By the sounds of it, he had better!
OK then disengage. HIS decisions are his alone. HE pays the consequences of those decisions. HIM!
He doesn't tell his work that he is imminently going to be a dad, and they send him abroad, then it speaks MASSIVE VOLUMES about him doesn't it? Give em enough rope and all that.
Imagine what people will think of HIM when they find out that he chose not to tell his work about the baby and missed the birth???
It'll reflect 100% on him and never, ever in a million years on you. Things like this are so serious as to permanently scar what people think of him, so there he is in a new job and everyone will KNOW he's a shit. Forever.
Don't panic about it, just get someone else as your birth buddy. I mean it. Don't let him have you on tenterhooks wondering and fretting if he'll be about for the birth. TBH, you don't need to additional pressure of a dickhead man-child faffing about not committing to probably the most important day of your life to date.
Get a Doula, or a really close relative to be with you and then relax. Be totally ambivalent toward him. Tell him "seeing as I didn't know if I could rely on you or not, I made alternative plans, if you are able to make it, great, if not, no biggie" you weasly little shite
These men dangle disaster over our heads, to get us to panic and cling on to them, pander to them and do what they want us to do. Our challenge is take a step back, know that nothing is actually a disaster, only if we let it. We need to see it for what it is, purely designed and targeted to cause maximum distress and chaos in our lives. Don't let them do this!
Look at the dangling disaster, and then get a sodding great big mental baseball bat and hit it out of the park.
Think about it, we can do it!
HOME RUN!