For months, the hospitalization and medical issues of Buffalo Bills and Sabres co-owner Kim Pegula were shrouded in mystery, the family saying only that she experienced "unexpected health issues" last June.

On Tuesday, Jessica Pegula, the world's fourth-ranked women's tennis player and daughter of Kim and Terry Pegula, revealed that her mother suffered cardiac arrest and is still recovering.

Jessica Pegula made the announcement in an essay she wrote for The Players' Tribune, titled, "I want to talk to you about my mom."

Jessica wrote that Kim Pegula is "dealing with significant expressive aphasia and significant memory issues."

"She can read, write, and understand pretty well, but she has trouble finding the words to respond," Jessica wrote. "It is hard to deal with and it takes a lot of patience to communicate with her, but I thank God every day that we can still communicate with her at all. The doctors continue to be blown away by her recovery, considering where she started, and her determination is the driving force of that."

Jessica credits her sister, Kelly, for saving the life of their mom, who went into cardiac arrest while she was sleeping around midnight on June 7, Kim Pegula's birthday.

"My dad woke up to her going into cardiac arrest and she was unresponsive for quite a while," Jessica wrote. "My sister gave her CPR until the ambulance arrived. She saved her life."

Paramedics restored Kim Pegula's heartbeat, Jessica wrote.

The revelation comes just more than a month after Bills safety Damar Hamlin suffered cardiac arrest on the field in a game against the Cincinnati Bengals on Monday, Jan. 2.

The life Kim Pegula returns to will not be the same as it was, Jessica wrote.

"She gave everyone so much of her time and effort. She lived it and loved it, and it was felt by everyone she met. Now we come to the realization that all of that is most likely gone. That she won't be able to be that person anymore."

Kim and Terry Pegula bought the Sabres in 2011 for $189 million and the Bills in 2014 for $1.4 billion. She is president of Pegula Sports and Entertainment, the umbrella organization for the Bills, Sabres, the Rochester Americans of the American Hockey League, and the Buffalo Bandits and Rochester Knighthawks of the National Lacrosse League.

--Field Level Media