What are my feelings about him?" asks Lisa Gastineau, contemplating her estranged husband, pro football star Mark. "I think he's a jerk. Period."

Certainly Lisa might claim provocation. For several weeks she looked on resentfully as Mark carried on his public courtship of Brigitte Nielsen. Then, finally, she'd had enough. No sooner had Mark announced to the world that he and Sly Stallone's former missus were not only engaged but that she was pregnant, than Lisa, who had been steeping in nitroglycerin, exploded into print, calling the relationship "pathetic" and the announcement "the epitome of bad taste." Why so? "There are a lot of people who can't control their hormones," she said, "but at least they have the decency to keep things quiet."

It is Lisa's contention that Mark, who achieved fame by mauling quarterbacks for the New York Jets, is guilty of unsportsmanlike conduct in the treatment of his 5-year-old daughter, Brittny. Lisa says Mark hasn't spoken to Brittny for nearly three months and that the little girl cried when told about Nielsen's pregnancy. "She doesn't want the baby," says Lisa. "It would be different if she and her father were seeing each other and if he were telling her, 'Listen, Brittny, I'm going to have another baby, but you'll still be my No. 1 little girl.' " For his part, Gastineau says Lisa is indulging in "self-serving public criticism," and adds, "I won't lower myself to that level."

There was a time when Lisa (née D'A-mico) was one of Mark's most fervent admirers. That was nine years ago, when she was introduced to him by one of his teammates, Marty Lyons. Fresh from her sophomore year at the University of Alabama, she remembers being "real impressed" with Gastineau. "Mark is smooth," she says. "He has more lines than a highway, and I thought he was good looking." Ironically, it was just a few months later, while they were watching Stallone in Rocky II at a drive-in, that Mark told Lisa he loved her. But the marriage was not harmonious. "I played the role of housewife," says Lisa. "Cooking, cooking and more cooking. Mark was never real big on the idea of a career for me." Her husband, she says, has "a very bad temper" and gave her little emotional support. "He leads a very narcissistic life," she maintains. For example: "He would shave all the hair off his legs and chest and arms so you could really see the muscle definition when he started working out. It was like sleeping next to a cactus."

Things really became prickly between them after Brittny came along in 1982. At that point, says Lisa, Mark became a major party animal and eventually began an affair with "a girl from Arizona." Mark's mother broke the news to Lisa. "She told me that the girl had been coming to football games in New York and sitting behind me," says Lisa. "I remember that every bit of life went out of me and hit the floor." The Gastineaus separated in June 1986, and Mark, on the downside of his football career, hitched his fading star to la Nielsen's.

Hard feelings aside—and she has plenty—Lisa wishes Mark would at least patch things up with Brittny. She won't be playing the dating game anytime soon herself, she says, but she knows a certain someone she finds very appealing. "I'd like to meet Sylvester Stallone," she says. "I think he's cute. But it's a little too close to home."

—By William Plummer, with Victoria Balfour in Huntington, N.Y.