Sheryl Sandberg says she's 30 years sadder and wiser following husband's death

Facebook Chief Operating Officer Sheryl Sandberg is marking the end of the Jewish mourning period following the death of her husband by opening up about her grieving experience.

"I have lived thirty years in these thirty days. I am thirty years sadder. I feel like I am thirty years wiser," the 45-year-old executive wrote in a lengthy post on Facebook.

Sandberg's husband, 47-year-old SurveyMonkey CEO Dave Goldberg died after slipping and falling from a treadmill while on vacation in Mexico on May 1, 2015.

Sandberg says during sheloshim, the less intense period of mourning that follows the seven-day shiva in Judaism, she came to better understand what it means to be a mother, both through seeing her children grieve and how her mother has helped her with her own grieving.

"She has explained to me that the anguish I am feeling is both my own and my children's, and I understood that she was right as I saw the pain in her own eyes," Sandberg wrote.

Sandberg, the author of "Lean In," says she has learned how to ask for help.

"Until now, I have been the older sister, the COO, the doer and the planner," she wrote. "I did not plan this, and when it happened, I was not capable of doing much of anything. Those closest to me took over. They planned. They arranged. They told me where to sit and reminded me to eat. They are still doing so much to support me and my children."

She says that transitioning back to work has been a "chance to feel useful and connected" and thanked the friends and strangers that offered her condolences and advice, as well as those who shared their own experiences with loss.

"I think when tragedy occurs, it presents a choice. You can give in to the void, the emptiness that fills your heart, your lungs, constricts your ability to think or even breathe. Or you can try to find meaning. These past thirty days, I have spent many of my moments lost in that void. And I know that many future moments will be consumed by the vast emptiness as well."

Sandberg says that going forward, she intends to choose meaning and life.