Hi there,
I've recently found myself in a very difficult situation regarding my Fiancé. He was detained in New Jersey after driving a car that had been reported stolen by a jaded ex. I have since spoken with the ex, and she has agreed to drop the charges, however he is now in trouble with immigration. He has overstayed a b2 visa, and could possibly be deported. My question is, should I have the ex drop the charges immediately, to have my fiancé be taken by immigration, or should the charges just remain for now? How long does it usually take for someone to be deported once they are seized by immigration? We are planning on getting an immigration lawyer. Has anyone been in a situation like this before?
Thank you in advance for any help anyone could give me.

I suggest contacting a lawyer 'immediately' if not sooner.

If he is guilty of the stolen car, it may show up as a felony and that makes immigration MUCH more difficult. Having current felony charges will not be in his favor. He is your fiancé, get married. This may help later on getting back in. He has a tie. Is he divorced, finalized?
You need an attorney to help with the cancellation of removal if possible. Check around, various prices, various amounts of work. Get an immigration lawyer that is familiar with the laws of immigration.