Why Brooke Shields Recently Apologized to College Boyfriend Dean Cain: I Was 'Paralyzed from Shame'

Ron Galella/Getty Dean Cain and Brooke Shields in 1995

Brooke Shields is opening up about wishing she'd lived more in the moment — and embraced her sexuality — during her romance with ex-boyfriend Dean Cain.

In this week's cover interview for PEOPLE, the actress, 57, recalls being in a "great relationship" with the "beautiful" and "mouthwatering" Cain, 56, while at Princeton University.

Yet as she explores in her upcoming documentary, Shields was sexualized early on in films such as 1978's Pretty Baby (where she played a child prostitute) and The Blue Lagoon (1980), an intense objectification which led her to disassociate from her body.

It also led to near-constant questions about her looks and sex life from the time she was a teen. "I was the most famous virgin in the world," she has quipped.

The intensity of the attention played out in her early romantic life — and her dynamic with Cain.

"We had a great relationship, broke up, got back together again after three years. And that should have been a delicious time for me of reveling in it and feeling proud and free because I was in love," she tells PEOPLE.

Never miss a story — sign up for PEOPLE's free daily newsletter to stay up-to-date on the best of what PEOPLE has to offer, from juicy celebrity news to compelling human-interest stories.

Michael Schwartz Brooke Shields on the cover of PEOPLE

RELATED: Brooke Shields Reveals She Was Sexually Assaulted 30 Years Ago: "I Blamed Myself"

"But it was as if I was just paralyzed from shame, thinking everybody was going to know, thinking of letting my fans down because I had professed one thing," Shields adds.

Before he was Superman on Lois & Clark: The New Adventures of Superman, Cain was Shields' football-player boyfriend and classmate at Princeton University.

The model and actress recalls of their relationship, "He just was so loyal and loving and just so in love. And I did not make it easy."

In fact, she tells PEOPLE, she even "apologized" to her ex "a few years back" for not enjoying the moment more.

"I said, 'I'm sorry for you, and I'm really sorry for me,' " Shields remembers.

RELATED VIDEO: Brooke Shields Opens Up in New Doc About Child Stardom and Sexual Assault: "It's a Miracle I Survived"

A mom to two daughters today — Rowan, 19, and Grier, 16 — Shields says she uses what she has learned from her own experience in communicating her hopes for them.

As she explains, "I want them to feel celebrated rather than shamed — shamed by their body, shamed by their sexuality."

"It's such a burden to carry," Shields adds.

Brooke Shields: Pretty Baby premieres April 3 on Hulu.

For more on Brooke Shields, pick up the latest issue of PEOPLE, on newsstands Friday.