Why doesn't he qualify for cancellation of removal (for lawful permanent residents) if he's been a permanent resident since '97?
You should try to "fight" the felony charge - you should retain a criminal lawyer who with consultation with and immigration lawyer will hopefully find a plea that the prosecutor will accept that is not a felony.
Need more facts.
Law Office of Luis A. Guerra (954) 434-5800. This answer is of a general nature and should not be relied upon as final, nor is it intended as legal advice.