He found fame with The Glass Menagerie and won Pulitzer prizes for his stage masterpieces, A Streetcar Named Desire and Cat on a Hot Tin Roof, but Tennessee Williams was plagued by self-doubt, previously unpublished letters reveal.

The American dramatist’s lack of confidence emerges repeatedly through his correspondence with trusted friends – his publisher, James Laughlin, and editor, Robert MacGregor – over 25 years until his death in 1983.

In 1964, he wrote of his “self-contempt”, adding: “I must confess that I have doubts and fears.” In 1972, he confided: “You know how badly I need reassurance about my work.”

His successes included screen adaptations of Streetcar Named Desire, starring Marlon Brando and Vivien Leigh, and Cat on a Hot Tin Roof, with Elizabeth Taylor and Paul Newman. But theatrical flops and the death of his lover, Frank Merlo, to cancer in 1963 took their toll on Williams, who found solace in drink and drugs, writing in 1969: “I am waking up late from a very bad dream … How terribly I have abused myself and my talent in the years … since Frankie’s death.”

In a poignant letter in 1960, he wrote: “I am tired of writing and writing is tired of me.” In 1970, he revealed that writing “came very close to destroying me”. Two years later, he mused: “I have been a writer nearly all my life … but it adds up to almost nothing.”

The correspondence will be published by WW Norton & Co on 13 April. The book, titled The Luck of Friendship: The Letters of Tennessee Williams and James Laughlin, casts new light on his life and work. The 170 letters have been edited by Peggy L Fox and Thomas Keith.

Keith said: “None of the witty, playful, serious and heart-felt letters in this volume from the last 25 years of their correspondence, 1958 to 1983, have ever been published before. The story that emerges is how Williams’s creative life flourished while his commercial success waned, how he maintained a strong focus on writing from 1963 to 1983 – in spite of his battles with drugs, alcohol and depression.

“That story is in dramatic contrast to popular narratives about how he was merely a man so drug and alcohol-ridden and diminished that he was unable to even function. Williams’s own voice along with Laughlin’s view of Williams create a more complex and richer understanding of what Williams was like after his critically and financially successful plays were behind him.”

The letters also reveal creative struggles. In 1973, referring to plans to publish his play Out Cry, which explores reality and illusion, he wrote: “Something will survive the Holocaust of these years of half-crazed, often impotent effort.”

In 1963, he expressed concerns about interpretations of his plays, including The Milk Train Doesn’t Stop Here Anymore: “I don’t want Milk Train directed by [Herbert] Machiz again. He camped it up too much. It needs more serious treatment.”

Keith said Williams’s friendship with Laughlin, a daring publisher who founded New Directions Publishing, bolstered him in his darkest hours. They gave strength to one another, despite each facing mental health challenges. Williams had depression while Laughlin was diagnosed with hereditary bipolar disorder. In 1963, Laughlin encouraged his friend: “These dark days will pass, even though at the moment things look black.”

When Williams was struggling to write in 1962, Laughlin offered advice: “I hope you will let yourself go in one play, be wilder, perhaps savager, pour out all your resentments at the state of things.”

Keith observed: “This is exactly what Williams then proceeded to do in plays like The Mutilated and Gnadiges Fraulein in 1966. Williams’s contribution to the worlds of theatre and literature was always, at its core, his portrayals of resilience, grace and endurance in the face of human suffering. He gave voices to, and told the stories of, the lost, defeated, sensitive, peculiar, defiant, and often invisible people who make up the bulk of humanity.

“In these letters, readers are reminded that Williams not only kept writing to the very end of this life, but that his lesser-known work, late plays, one-acts, and critical failures are now part of the canon of his writing.”