Former first lady Barbara Bush, though in failing health and refusing further medical treatment, remained in "great spirits" during her final days, according to her granddaughter Jenna Bush Hager. In fact, as of Monday night she was alert and having conversations over a bourbon, a source close to the Bush family told CBS News.

The former first lady, 92, had been through a series of hospitalizations and decided not seek additional medical care. She had been suffering in recent years from congestive heart failure and chronic obstructive pulmonary disease (COPD). COPD makes it difficult for her to breathe, according to the source. On Monday, Hager said that her grandmother and her grandfather, former President George H.W. Bush, are surrounded by family.

Bush's son, Neil Bush, told CBS Houston affiliate KHOU-TV Monday that his mother was still able to enjoy one of her favorite pasttimes, reading.

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"As my mom has become more and more frail -- she's not able to walk anymore and take her dogs out and that kind of thing -- we have quality time and we're sharing this quality time with other family members and friends that come by to read," Neil Bush said.

He choked back tears as he said he is rereading his mother's memoir and has a new appreciation of her life.

"And to read the story of their amazing life together has been a remarkable blessing to me personally as their son," Neil Bush told KHOU-TV. "And a reminder of just what a fabulous woman she is and what a great life they've lived and what a great life we've experienced and how much they've done for so many others, including her favorite topic, which is literacy."

CBS News' Jenna Gibson contributed to this report.