How do you co-parent with your STBX if he won't communicate at all with you?

Hi. I have been in the divorce process since February and haven't made any progress because my stbx pretends that nothing is happening. He blames me that the judge ordered him out of the house (for calling me names in front of kids, stealing my cc, not paying his share of bills etc) and has told the kids that he lives in his car (in the winter in IL) because their mommy has taken all his money. He refuses to return any emails regarding selling the house, spending time with kids during holidays etc.. because he said "I never want to speak or deal with you again". He has had a settlement agreement from me since May and each time we ask him to respond he says "it is blackmail and extortion that doesn't even deserve a response". I explained that we will have to go back and forth several times to come to an agreement but he says he doesn't agree to anything. In the meantime his attorney has quit, he doesn't show up for court (costing me thousands), and tells the kids he might have to move to another country because he doesn't have any money. I have two little boys and they don't know what to believe. All they say is that Dad is "trash tallking" about me when they see him and says that "your mother has destroyed our family. FYI, he asked for the divorce when I found out about other women and thousands upon thousands of debt he had that I didn't even know about. He wouldn't file so I did and he has tried to blame it all on me and keeps putting the kids in the middle since. Now there is a child advocate attorney to help determine custody (another component neither one of us can afford). How do you deal with someone like that???