Inside Meryl Streep's Bedside Vigil for Dying Boyfriend John Cazale and How She Found Love Again with Don Gummer

When Meryl Streep‘s boyfriend John Cazale died of cancer in 1978, the actress was devastated. But, as it sometimes does, love and light came out of the tragedy – in this case, quite quickly.

Streep’s two-year romance with Cazale, a talented actor who starred in five Best Picture nominees in just six years, is detailed in Michael Schulman’s upcoming biography Her Again: Becoming Meryl Streep, published April 26 by HarperCollins.

Get push notifications with news, features and more.

Meeting first during an audition for New York City’s famed Shakespeare in the Park, Streep and The Godfather star’s connection was obvious to their castmates and director Joe Papp. Schulman writes that the pair’s romance was intense – and physical, with Streep’s consistently chapped lips drawing attention from the crew.

It was during their work on The Deer Hunter – his final film – that Cazale got sicker and sicker and Streep morphed from lover to nurse. For five months she accompanied him to chemotherapy treatments at Memorial Sloan Kettering Cancer Center, and barely showing her strained resolve.

“Meryl stayed by his side every single moment,” The Deer Hunter director Michael Cimino told PEOPLE in 1995. “By her devotion to John, I knew she had great courage.”

During Cazale’s final days, Streep stood by his bedside in their Manhattan apartment constantly, performing comedic routines and reading from the newspaper in faux voices, according to Her Again.

“She took care of him like there was nobody else on earth,” Joe Papp said of Streep’s commitment to Cazale, Schulman writes. “She never betrayed him in his presence or out of his presence. Never betrayed any notion that he would not survive. He knew he was dying, the way a dying man knows it. She gave him tremendous hope.”

When Cazale passed on March 12, 1978, Streep was so overcome with emotion that she collapsed into him and began pounding on his chest, crying for him to wake up. And for a quick second, Cazale opened his eyes and reassured Streep she would be okay before finally closing his eyes for the final time, according to the book.

Meryl Streep’s Changing Looks!

A year after his death, Streep addressed his passing in an interview with PEOPLE.

“The death is still very much with me. It has forced me to confront my own mortality, and once you do that, you look at things differently,” she said.

Streep, according to Schulman, briefly escaped her woes and stayed with a friend in Canada, eventually returning to the city only to find herself unceremoniously kicked out of the loft she had shared with Cazale.

Faced with packing up years of physical memories, Streep’s brother arrived to help – with friend and sculptor Don Gummer in tow. It wasn’t love at first sight, but it certainly didn’t take long, says Schulman.

Corresponding at first through letters while Gummer traveled, a then 29-year-old Streep soon realized the artist wanted something more. When he returned, Streep took up residence in Gummer’s apartment and began the difficult filming experience that was Kramer vs. Kramer – a role that would eventually lead to her first Oscar.

And then, just six months after Cazale’s death, Gummer and Streep were married in the garden of her parents’ home in September 1978. While friends questioned whether the relationship was a rebound, her mother had larger concerns, wondering, according to Schulman, “What is she thinking about?”

While the quickie marriage strained Streep’s relationship with her mother, any worries were ultimately for naught: Through nearly 38 years of marriage, four children (Henry, 36, actresses Mamie, 32, and Grace, 29, and Louisa, 24) and 17 more Academy Award nominations, Gummer and Streep have stayed together.

In 2012, Streep honored her husband and their long union as accepted the Best Actress Academy Award for her role in The Iron Lady.