You should also notify USCIS that you filed a joint petition and are now separated. They will send you an RFE asking if you want to switch to a divorce waiver petition. You do.
The most important thing to remember about divorce is that you only get one shot at it. First you try to come to agreements together, whatever you cant decide on the judge can rule on. So try first to come to an agreement, if you can not its okay. You can have the judge review each of your positions and evidence and rule on the issue you are disagreeing on.
