Marina Oswald Porter, hesitant and almost expressionless, held a press conference yesterday to boost sales of a book about her life and her first husband, Lee Harvey Oswald. The book, "Marina and Lee," has a photograph of the couple inside a heart-shaped frame on the cover. It is the jacket copy says, "A fascinating and richly detailed portrait of a man who was driven to kill and a woman who was determined to survive."

"My regret through the years has . . . been immense." Porter told the assembled reporters as photographers took picture after picture of the short, slim woman who is thinner now than she was when her husband assassinated President Kennedy in Dallas on Nov. 22, 1963. "I can never forget or forgive what he (Oswald) did, to me and to my children, to the President and his family, to the whole world," she said.

She stood behind a lectern bristling with microphones and answering patiently as reporters probed for a bit of news and new psychosexual theory about the assassination that troubles Americans' memories as perhaps no other event has done.

"It was a sad life," she said when asked to characterize her more than two years of marriage to Oswald. "A quite difficult marriage . . . and problems from a financial point of view that didn't make things easier."

"How do you feel about Oswald?", reporters asked against and again.

"You forget with the years about the bad and troublesome times," she replied. But, when she read "Marina and Lee" for the first time two weeks ago it made her angry at him.

A reporter remarked that she seemed to know more about Oswald from reading the book than from her life with him.

Porter, who spent nearly seven months with the book's author Priscilla Johnson McMillan in 1964, explained again that she had forgotten many of the bad time until she read the book.

Reporters pressed her to say she feels hatred for Oswald. She agreed that some of what the feels could be called hate.

A questioner reminded her that at one time duringher marriage to Oswald she had felt a sexual aversion to him. Perhaps, he suggested, Oswald had killed Kennedy as a result of sexual frustration.

Porter rejected the suggestion.

Another reporter wondered whether Oswald had been jealous of Kennedy because his wife admired the President. He proposed that it had been a triangle in Oswald's mind with the two men competing for her love. She did not take the theory seriously.

Marina Porter rarely changed expression as she turned her head and stared at each questioner. Employees of Harper & Row, the publisher of "Marina and Lee", groaned at some of the questions.

When McMillan was responding in a circutous manner to a question about Oswalds mental health. Oswald's widow broke in: "Nobody in his right mind would kill someone."

"Of course," Porter responded when asked whether she ever thought of Kennedy's widow. "I always feel sorry for a woman who loses her husband."

She explained that it is difficult for a woman alone to earn money and raise children.

But, she was asked, didn't she feel a special grief for Jacqueline Kennedy Onassis?

"For her and for me, too," Marina Porter replied levelly. "I'm sorry, but sometimes I do feel sorry for myself."

her two children ask questions about their father, she told the press conference, and only then does she speak of him. "They ask, 'Did he ever play with me? Did he love me?' and things like that," she said.

A reporter said that the children must face a lost of questions from their schoolmates.

"What questions can they ask a child about a father he doesn't remember?" she replied.

In a prepared statement, Porter said that anyone who reads "Marina and Lee" "Will see that the events of Nov. 22, 1963, had to happen. It was the final act of a slow, painful tragedy that was our life together."

She was unable to clarify at the press conference why the assassination "had to happen." Her husband had a violent temper and was a loner who acted along in killing Kennedy, she said. But the 36-year-old woman, who will share in the book's royalties, made it clear that many of the details of her life with Oswald no longer stand out in her memory. A Harper & Row spokesman refused to say what percentage of the Royalties she will get.

After 30 minutes of questioning, with the reporters' zeal to find fresh news or just to hear Marina Porter continue talking apparently undiminished. Harper & Row editor-in-chief Buz Wyeth cut the press conference off. A couple of the reporters and photographers asked Porter for her autograph before Wyeth could escort her from the room. CAPTION: Pictures 1 and 2, Marina Oswald Porter, and Priscilla Johns on McMillan at the press conference. Lee Harvey Oswald believed to be in April, 1963. [TEXT ILLEGIBLE]