She called him "a fraud and a phony." He called her "a disaster" and said "ambition kissed her on the lips."

It was another episode in the summer soap opera of what passes for politics lately in the nation's largest city. The tabloids dub it the "Ed and Carol Show." City Council President Carol Bellamy calls it "a family feud."

Today, in the first face-to-face debate of the mayoral contest between Bellamy and three-term incumbent Edward I. Koch, 2,000 New Yorkers cheered, booed and heckled as the two candidates unceremoniously slugged it out, interrupting, shouting and slandering each other with relish.

A third contender, Assemblyman Herman D. Farrell, called the differences between Koch and Bellamy "superficial" and chided the two for focusing on "who can outdo whom in political invective." Farrell, the only black in the campaign, was knocked off the ballot recently when Bellamy challenged his filing petitions.

Adding to the chaos in the Sheraton Center hotel ballroom were rival demonstrations by Feminists Against Pornography, at least two tenants' organizations and various unions. A supporter of perennial right-wing presidential candidate Lyndon LaRouche was carried off the stage, arms flailing, as he tried to disrupt the proceedings. Later, laughter erupted and politicos wagged their heads knowingly as Bellamy's microphone failed during an anti-Koch stemwinder.

Despite the sound and fury, however, knowledgeable New Yorkers were left wondering whether it signified anything. Koch, the overwhelming favorite, has raised a $5.3 million war chest, mostly from real estate and financial companies that have fared well during his tenure. Bellamy has raised slightly more than $700,000. Koch has saturated the airwaves with television commercials. Bellamy has hardly enough money to go on the air.

A Daily News poll two weeks ago showed Koch leading Bellamy by 48 points. The Democratic primary, tantamount to election, is Sept. 10.

Nonetheless, Bellamy took the offensive during today's debate, out-Koching the normally acerbic Koch, who, warned by chief campaign adviser David Garth to keep his famous mouth shut, was only insulting enough to maintain his reputation.

"Bellamy took command of the situation," said former mayoral aide Kenneth Lipper, a candidate for city council president. "But all Koch had to do was come out whole. You know how it is when the clock is ticking at the end of the basketball game? The winning team just keeps dribbling."

Bellamy attacked Koch for changing positions on issues such as Westway, a multibillion-dollar highway and real estate development, which he once opposed and now favors, and on commercial rent control, which he once favored and now opposes.

"Where is the old Ed Koch?" she demanded, charging that the man who once rode the bus from his rent-controlled apartment now goes to "book-signing parties in a Lincoln limousine." Koch wrote a best-seller, "Mayor," which was turned into a musical now playing in Greenwich Village.

Later, in a reference to the mayor's well-known gourmet palate, she inquired, "Have you been to a Nedicks or a Roy Rogers?"

Koch said Bellamy had voted for the tax-breaks for developers that she was now trying to pin on him. As for her record, he asked the audience, "Do you remember what she did in city council? None of her colleagues can."

The mayor also noted that Bellamy had endorsed his candidacy for governor in 1982 against Mario M. Cuomo. "She said I'm a good manager," Koch said. Now, he said, responding to Bellamy's accusation that he had "lost control" of the city, "Is this political hypocrisy, a change of mind, a flipflop . . . . . ?"

As for Bellamy's charges that he has neglected the subway system, Koch said that as a member of the Metropolitan Transportation Authority board, Bellamy "was a disaster . . . . She was on the board when the tunnel to nowhere filled up with water. You were there and doing nothing but fiddling," he told her, referring to the multibillion-dollar 63rd Street tunnel, recently halted in midconstruction by federal authorities after it sprang leaks.

While Koch was busy accusing Bellamy of "street theater" and Bellamy was charging that "instead of competence, we got comedy" from Koch, Farrell nearly stole the show with his own one-liner. In a statement advocating public schooling from the age of three, Farrell said he had gone to school as a 3-year-old and had learned to read by the age of 4 1/2 -- "and I'm not a very bright person."

He insisted later that the aside will not hurt his candidacy, which he is pursuing in the courts.

"You think anybody believed me?" he asked. "Koch's humor is always at other people's expense. My humor is always at my expense. That's the difference between a mensch [Yiddish for "good guy"] and a wimp."