Wow - so sorry you are here, but you are in the best possible place for support. A few things for you to chew on:
1) Have you filed an order for temporary support? If not, see an attorney and get the ball rolling.
2) Did he sustain any concussions when he was in the military? CTE - chronic traumatic encephalopathy, like NFL players get - can also be seen in military personnel who have sustained concussive head injuries. PTSD is also a possibility. You may not be able to do anything about it, but knowing that he has a brain injury may help you deal.
3) Do you suspect an affair? Men seldom leave before they have another woman lined up.
4) On his criticisms - ONLY TAKE THOSE THINGS YOU KNOW TO BE TRUE! This can be a great opportunity to grow and change, but the WAS also often has to demonize the LBS in order to justify their own behavior. You had four children and a military husband - it was appropriate for you to be a SAHM. Don't second guess yourself - your kids needed you. He just wants you to work now so that he won't have to pay you as much alimony. Let it roll off of you and do what you need to do for you and your kids.
5) Take the high road. Whatever is going on with him, he's not in his right mind. He may or may not ever return to normal. Start working on making a good life for you and the kids and let him go through whatever he's going through, but hold your head up high and don't let him drag you into the mud with him.
