All he wanted to do was sell his former fiancée’s $30,000 engagement ring and get on with his life.

Instead, David Cushman told a Manhattan jury yesterday, he got Maced in a Christopher Street vestibule by a man who had answered his Craigslist ad and called himself John.

“I was not able to see. I was coughing. I felt like I wanted to puke,” the 31-

year-old salesman said, accusing alleged ring worm Gerard DeGerolamo of a spritz-and-swipe scheme.

DeGerolamo, 67, is a Lucchese crime-family associate, FBI sources say. He allegedly also tried to rob a 33-year-old woman going through a divorce and offering on Craigslist two diamond rings her husband had given her.

“He was targeting individuals who were selling expensive jewelry and . . . going through a traumatic time,” prosecutor Steve Pilnyak said last week.

Cushman said he tackled DeGerolamo and got back the ring.