Something’s rotten in the Big Apple!

Ramona Singer has reacted to a report which alleged that her husband Mario carried on an illict affair with a woman four decades younger than he is -- and got her pregnant!

According to the New York Post, the Real Housewives of New York City husband has been stepping out with a young mistress behind the back of his wife of 27 years.

The woman, a blonde in her 20s, allegedly met him in the Hamptons over the summer and in a sensational development, the paper said, she became pregnant in August.