Now that’s a bitter divorce.

The feds arrested a Long Island bartender yesterday after they say he sent his ex-wife a series of alimony checks in the mail that were smeared with feces.

Gerald Desiderio, 51, who lives in Garden City and works as a bartender in Elmont, was charged by Brooklyn federal prosecutors with sending hazardous materials through the US Mail, obstructing the mail, and interstate stalking.

Postal inspectors say over the past year, Desiderio has also enclosed harassing and vulgar notes and tasteless objects along with the alimony checks that he sent to his ex in Arizona – including a photo of a knife with a serrated blade.

The ex-wife told authorities that she had moved from away from New York and resettled in Arizona out of fear and to escape her ex-husband’s persecution, officials said.

Desiderio was arraigned yesterday in Brooklyn federal court, where he posted $35,000 bail and was released.

He will face a federal court trial in Flagstaff, Arizona later month, officials said.

mmaddux@nypost.com