First thing is to freeze credit with all three major CRA's. That at least should stop the damage from expanding to new items.

A good chance that if the fraudster had a fake ID, they also used it to obtain a credit card and other documentation in your name. Thus, tracking all of this down is important.

Hopefully you have identity theft insurance, either as a standalone (preferable) or as a throwaway with a credit card or some other policy. This can be helpful in defraying losses and, in most instances in getting the work done.