jill zarin shared a heartbreaking update with "RHONY" fans, posting an Instagram message that gave an update on her husband's cancer battle as he reportedly nears the end.

The reality television star celebrated her birthday this week, and posted a picture on Instagram of a beautifully crafted, layered cake. In the update, Jill Zarin noted that she has been trying to take advantage of every moment since her husband was diagnosed with cancer. The "RHONY" star said that he continues to "astound doctors" with his progress against the cancer, but the message itself was bittersweet given his grim prognosis.

"I am most grateful to God who continues to give Bobby and me more time together," she wrote.

"When Bobby always said to me 'cherish the moment' I never knew the power of that message until now."

Jill Zarin added that she and Bobby are continuing to fight against his Anaplastic Thyroid Cancer and that Bobby has astounded his doctors with his determination to fight the disease despite long odds against him. The "RHONY" star also thanked friends and fans for their many messages of support, saying she reads all of them to gain strength during the difficult battle ahead of the couple.

Bobby Zarin's cancer progressing

Jill Zarin's husband had originally been diagnosed with thyroid cancer close to eight years ago, but it has recently surged back and now spread into his brain, the "Real Housewives of New York" star shared with fans. Those close to Jill Zarin said that Bobby's outlook does not look good [VIDEO], but she is trying to remain positive during his cancer battle.

It has been a difficult road [VIDEO]for Bobby, with People magazine noting that he also had to undergo Gamma Knife Radiosurgery at the noted MD Anderson Cancer Center in Houston.

Jill Zarin staying by her husband's side

While Bobby Zarin has a difficult battle ahead still, his wife will be there to support him. A source close to the couple told Radar Online earlier this month that Jill has been hesitant to go to public events as her husband's health declines. The source claimed that Jill Zarin has been by his side constantly, but that Bobby insisted she leave to make a brief appearance at a recent event.

As Bobby Zarin continues to battle cancer, Jill Zarin has pulled back on her other obligations, including appearances on television. Once a staple on "Real Housewives of New York," she has returned only briefly since her firing more than three years ago.