Hi Jpeg, my W is a "kitty-cat" MLCer. There is no anger, few arguments. She is up-front about her dating, and her R with om. There is also depression though.
I started paying child support before the court became involved 6 months later. I guess my setting a good tone at the start helped in our sitch and was helpful in not having a written agreement in place.
I would make sure that your lawyer understands what you want from your separation. Your state's rules on the quick divorce if a written separation agreement is in place seems really counter-productive. There could be other options. But making sure your H pays his share of the bills is really important. He must be spending his $$$ somewhere, you just need to make sure that you are a higher priority.