The max sentence for a C felony is 5-15 years, however, the facts you describe seem unlikely to result in significant jail time. I'm a former Westchester DA, and while the office takes Domestic cases (husband/wife, etc) very seriously, if your friend has no prior criminal record, they will probably be willing to deal fairly with him on this case.
If he hasn't done so already, he should look to hire an experienced criminal lawyer who practices in Westchester.
Should you have any further questions, please feel free to contact me at anytime.
Pursuant to § 140.25, a person is guilty of burglary in the second degree when he knowingly enters or remains unlawfully in a building with intent to commit a crime therein, and when: 1. In effecting entry or while in the building or in immediate flight therefrom, he or another participant in the crime:(a) Is armed with explosives or a deadly weapon; or (b) Causes physical injury to any person who is not a participant in the crime; or(c) Uses or threatens the immediate use of a dangerous instrument; or (d) Displays what appears to be a pistol, revolver, rifle, shotgun, machine gun or other firearm; or 2. The building is a dwelling. Burglary in the second degree is a class C felony. For an adult first time felony offenders the minimum is three years and the maximum is fifteen years. See: Penal Law 70.00. I strongly urge your friend to exercise his right to remain silent and his right to a lawyer. If he cannot afford an attorney, he should request that the Court appoint the public defender.