Cissy Houston, mother of the late Whitney Houston and an iconic gospel singer herself, has died. She was 91.

Houston died at her home in New Jersey on Monday, Oct. 7 while under hospice care for Alzheimer's disease, her daughter-in-law Pat Houston confirmed.

“Our hearts are filled with pain and sadness. We loss the matriarch of our family,” Pat said in a statement. “Mother Cissy has been a strong and towering figure in our lives. A woman of deep faith and conviction, who cared greatly about family, ministry, and community. Her more than seven-decade career in music and entertainment will remain at the forefront of our hearts."

Pat continued, "Her contributions to popular music and culture are unparalleled . We are blessed and grateful that God allowed her to spend so many years with us and we are thankful for all the many valuable life lessons that she taught us. May she rest in peace, alongside her daughter, Whitney and granddaughter Bobbi Kristina and other cherished family members."

Houston was also an aunt of singers Dionne Warwick and Dee Dee Warwick.

Houston began her singing career in 1938 when she joined her sister Anne, and two brothers Larry and Nicky in a group called the Drinkard Four.

In 1963, she formed a group called the Sweet Inspirations with Dee Dee Warwick, her niece. Within a few years, the band was providing back-up vocals for artists like Otis Redding, Dusty Springfield and Wilson Pickett. They later worked with The Jimi Hendrix Experience in 1967 and Elvis Presley in 1969.

As a soloist, Houston released her first solo record titled "This Is My Vow" in 1963 — however, in her earlier records her name was spelled "Sissie" Houston. She released her solo debut LP Presenting Cissy Houston in 1970 — which included hits such as "Be My Baby" and "I'll Be There." In 1972, she sang back-up on Bette Midler's debut album.

Houston won two Grammy awards in her lifetime, in 1996 for best traditional soul gospel album for Face to Face and in 1998 for album He Leadeth Me.

"Cissy had an incredible voice and that transferred to her little baby, Whitney," Warwick told PEOPLE in February. "Whitney came up exactly the way we all did, in the church choir. It was just preordained, she was going to sing. Her destiny was as was the rest of the family. As if God pointed a finger at us and said 'Let them vocal cords do what they got to do.'"

"Watching Whitney was like seeing Cissy grow up again. The voice; the dedication," she continued. "Every little girl that came along after her wanted to be Whitney Houston."

Cissy Houston and Whitney Houston

She also recorded a duet with daughter Whitney titled "I Know Him So Well" in 1987. In 2006, she recorded "Family First" with Dionne and Whitney.

Houston was married to an NBA basketball player, Gary Garland from 1955 to 1997 and they share son Gary together. In 1958, Houston met John Russell Houston, father of Michael and Whitney. The couple legally separated in 1991 and had six grandchildren and nine great-grandchildren.

In 2013, the star released a revealing memoir titled Remembering Whitney, where she wrote candidly about Whitney's severe drug problems and the downward spiral that led to her death by drowning in a hotel bathtub with traces of cocaine still in her system in February 2012.

"She started partying and she didn't really know how to stop," she wrote. "I used to wonder what she was doing at night, where she was."

But when she tried to contact her, Whitney often didn't return her call.

"Whitney hid from me," Houston said. And when she did see her, she was often afraid to confront her daughter.

She also admitted she was still tormented by her daughter's sudden death. "I'm angry she died alone, in those conditions," she says. "I'm still mad about that."

Cissy Houston

Nearly five months following her death, Houston paid tribute to Whitney at the BET Awards by performing a rendition of "Bridge Over Troubled Water.

Music producer Maureen Crowe remembered Houston in a statement to PEOPLE.

"Cissy Houston was a powerful vocal icon whose standards are felt today. She taught Whitney how to sing and the generations that followed. The Whitney tribute at the 50th Anniversary AMA Sunday night was also a tribute to Cissy. She is seen sitting by Whitney's side, year after year. At every win, Whitney thanks Cissy and John for their support in making her dreams come. She dedicated her life to her family, her faith, and to music. My heartfelt sympathies go to the family."