
Quoting
Mr. Knowitall
He would file for divorce where he is presently domiciled. You are telling us that's Detroit.
It's possible to complete the divorce with neither of you represented by counsel, one of you represented by counsel, or both of you represented by counsel. The costs will depend upon whether or not one or both of you hire lawyers. You can look up filing fees on the court website.
If you're living in Germany and he's in Detroit, you're already separated. But there is a sixty day waiting period (that you can ask the court to shorten) for a divorce that does not involve kids (180 days with kids).
Somebody will have to appear in court for the divorce to go forward. It's possible for him to file and handle all of the appearances, while you remain in Germany. It will be up to you whether or not you trust him to do that or if you want to either travel to the U.S. for court or seek legal representation.