Sarah Jessica Parker often plays exactly the opposite of who she really is.

When she debuted as the now-iconic single woman Carrie Bradshaw in Sex and the City in 1998, she was in fact a newlywed — she had married Matthew Broderick a year earlier. And while they’ve since celebrated their 20th wedding anniversary, she stars on HBO’s Divorce, now in its second season, as a newly single mom struggling to launch a career.

Covering this week’s issue of PEOPLE, the actress opens up about everything from her relationship, raising three kids and surviving the ups and downs of life in the spotlight.

“I think marriage has a lot of vitality,” she says. “If you’re fortunate, it’s like this dazzling organism.”

Parker, 52, and Broderick, 55, dated for five years before they wed. The pair made it official on May 19, 1997, after inviting 100 of their closest friends to New York for what the guests thought was a party. Instead, Parker walked down the aisle in her now-iconic black wedding dress. Since then, the two have become parents to 8-year-old twins Tabitha and Loretta and son James Wilkie, 15.

Asked if there was a specific moment she realized Broderick was the one, Parker admits she “had never thought about it.”

“I never thought about a wedding dress. Never. Had not one daydream about it,” she says. “At one point I just simply remember thinking, ‘God, I really hope he asks me to marry him.’ I don’t know when or why. It was fairly early on.”

For much more on Sarah Jessica Parker, pick up this week’s issue of PEOPLE, on newsstands Friday 

As for how they keep their marriage happy after two decades?

“I feel like it changes,” she explains. “Your needs are shifting. You and your partner are going to change. It seems so silly, but I think you’re very lucky if you like the person. I still just really like him. I’m sure I annoy him and he annoys me, but I literally learn about him every day. I’m like, ‘You’re doing what? You’re reading what?’ ”

And when it comes to raising their children, Parker says she and Broderick make a point to “have conversations” as a family.

“Our lives are unpredictable, and we’re not always here when we want to be,” she admits. “We can’t always do drop-off and pick-up. But I’m proud that our children talk to us in the way they do. I’m glad they’re curious people.”

James Wilkie, Parker reveals, has “this great friend group.”

“Sometimes I just sit on the stairs because they’re all in the kitchen, eating all the food, and I listen,” she says. “And I’m so charmed by their conversation. I’m so happy with the young man he’s becoming.”

Parker says Tabitha and Loretta have established such separate identities that she forgets they’re twins.

“They have different interests,” she says. “They’re really devoted to each other, but they’ll also say, ‘I need time away from her.’ Tabitha can play by herself for hours. Loretta always needs to be checking in. They go to different schools. That’s Tabitha’s idea.”

And all while juggling motherhood, Parker has become a one-woman empire: In addition to fragrances and SJP Collection shoes, she has teamed up with GAP to create a limited-edition children’s collection, available March 1, and will be launching her own book imprint, SJP for Hogarth, in June. But she still carves out time for herself.

“I read. I always try to find time. Waiting for a child. I read on the subway,” she says. “On the set, I have a book hidden under a dress or under a couch. For me reading is like disappearing. It transports me. And when I get into bed, I watch TV. I love TV. I love the news. It drives me bananas. I love watching Rachel Maddow. I love House Hunters International. I love Dateline. I love 30 for 30 on ESPN.”

RELATED VIDEO: Sarah Jessica Parker Reveals Exactly What It’s like to Watch Divorce with Husband Matthew Broderick

Looking ahead to her future with Broderick, Parker says she “definitely” sees the couple doing plenty of traveling.

“I’ve traveled so much, but more often than not without Matthew because it’s been for work,” she says. “I can’t imagine that I don’t want to be working in some way, because it just brings me so much joy. I still love acting. Sometimes I look at Ruth Gordon and think, you know, she was doing what she loved.”

—With AURELIE CORINTHIOS