Whitney Houston's Mother, Cissy Houston, On Singer's Drug Use, Lesbian Rumors

Whitney Houston died nearly one year ago and her mother, Cissy, continues to ask herself: "Could I have saved her somehow?"

In a her new tell-all memoir, "Remembering Whitney," Cissy reveals intimate details about her daughter's highs and lows.

"I'm angry she died alone , in those conditions," writes Cissy, according to an excerpt obtained by People magazine. Whitney drowned in a bathtub at the Beverly Hilton Hotel on Feb. 11, 2011, at 48 years old. Drugs were found in her system, a habit Cissy knew about. "She started partying and she didn't really know how to stop. I used to wonder what she was doing at night, where she was."

Cissy also delves into Whitney's relationships and rumors that she had a lesbian romance with her former assistant and creative director, Robyn Crawford.

Rumors had circulated since the 1980s that the two, who met when they were teenagers in New Jersey, were more than just friends. When Whitney died, Crawford penned a touching tribute to the "I Will Always Love You" singer for Esquire.

Cissy's feelings on Crawford, however, seem strained. She writes: "I just didnt want her with my daughter. I know nothing about a romantic relationship. That's what everybody said but they didn't know either."

Since her daughter's death, the 79-year-old, whose book hits shelves on Jan. 29, has had to deal with keeping her granddaughter, Bobbi Kristina, grounded.

Some thought Bobbi could be headed down the same path as Whitney after dealing with the death. Cissy attempted to keep a $20 million inheritance from the teenager, because she thought it was "too much, too soon," according to TMZ. The two reportedly settled and are ready to move forward.

Cissy will sit down with Oprah Winfrey on Jan. 28 for her first in-depth interview since Whitney's death for "Oprah's Next Chapter."