Wow...this is a messy situation. I also have a divorce decree issue for a Visa that was refused, but mine isn't as complex as yours. I was divorced 18 years ago, but didn't think to provide that document to my fiance in the Philippines. Either way, the Embassy person not only wanted proof that I divorced 18 years ago, but they wanted an original document. Luckily, my ex-wife still lives in the state we were divorced, so she got the documents and mailed it to the PI...once they get it, we'll be approved.
That being said, I agree with others that say you might need to get properly divorced from your first husband and apply for the spousal Visa. Don't be surprised if it still causes issues along the way...but at least you'll have the official divorce. On top of the process taking time, everything has to look right and anyone who reviews your case will look for something like this to deny the Visa. I have a sense you're in for a long ride...but stay patient.