I learned to call a Moratorium on major decision making when stressed out... a long time ago. Following countless and profoundly regretted choices. Hey, even a jarhead can learn... eventually. ;)
My suggestion would be to ask him to wait a year. If he still wants a divorce in a year you’ll give him one, with no argument, no questions asked. Until then, you don’t want to just roll over, & want to fight for him, and fight for your family, and you want him to fight... instead of making decisions in pain he may come to regret later. Doesn’t mean he has to start fighting right now, you understand being tired, that’s why you’ve given him everything he’s asked for to date. But? He can do a year, standing on his head, and he owes it to THIS team to see if shit can get squared away. He wants a plan? Here’s a plan. Give it a year, and then decide. In the meantime, you can live separately, coparent, the whole 9.
A whole helluva lot about dealing with PTSD -in my experience- is about creating delaying actions & rally points. Giving yourself time to get through hard shit, whilst protecting what you stand to lose, time to regroup... instead of making hard things harder. Sadly, it takes time to learn that just because it feels like now is forever, doesn’t mean it’s true. I used to nuke my life and walk away from the world pretty damn regularly. It took me years to learn that what felt solid, was probably only going to last -on the outside- 6 weeks to 6 months. And could easily last far less. That’s not forever. Hell. Sometimes? That’s just a vacation.
He might not change his mind in a year. You might change your mind in a few months. But if you can get him to slow down instead of rushing through? There’s at least a fighting chance. Slow is smooth, smooth is fast, fast is lethal... can be easy to forget. The impulse when anxiety/rage/fear is running hot is to go-go-go. Ain’t usually the smartest thing to do.