Last year I journeyed to the precipice of death. It was a horrible trip, ending in the loss of my sister-in-law, Ali.

Then I returned for another visit.

The day after Ali’s funeral, following her death from a variant of ovarian cancer, a CT-scan confirmed my own diagnosis. As Ali died, I began my own battle with the same disease. Ali was 47; I, 46.

The anniversary of that terrible week is upon us, and I still can’t wrap my mind around any of it — that Ali is gone; that for much of this year I was a cancer patient; the bizarre concurrence of these events. As the Yiddish proverb tells us, “Man plans, God laughs.” Expect the unexpected.

And yet, even now, after an apparently successful treatment of my cancer, I am so focused on survival that I can’t dwell on the strangeness of this life chapter. Instead, I plant one foot in front of the other, seeking balance and calm.

In this preoccupied state, I haven’t been able to properly mourn my sister-in-law. The psychiatrist Elisabeth Kubler-Ross has a name for the phase of bereavement where I find myself stranded: denial. “But really, what’s wrong with denial?” I ask a friend, who years ago dealt with the death of a family member shortly before her own diagnosis of breast cancer. We decide that what protects us from the deepest agony of loss can’t be all bad, except that the hurt can surface suddenly. When my nephews stay over one night in December, I immediately think to call Ali to reassure her how well her sons are faring.

And yet, even as I delude myself into believing that Ali’s absence is merely temporary, at times it seems as if Ali’s spirit has taken up residence in my brain. Whenever I’m confronted by a cancer conundrum (several times daily), I wonder: “What would Ali do?” The sickness stole so much: her hair, her ability to walk outside, her chance to watch her boys grow up. It never touched her grace.

I have many “guiding lights” in my confrontation with serious illness, including Rochelle Shoretz, who founded Sharsheret, the nonprofit devoted to aiding young breast and ovarian cancer patients. Rochelle, who died this past spring, could run circles around most people with her vibrancy and intelligence, and literally ran marathons even after her diagnosis of advanced breast cancer.

But, for many years, it’s seemed to me that Ali has a led a sort of parallel life to my own, a Park Slope version of my Upper West Side experience — “this is how we do it on the Slope” she would say with a shrug, her emphasis on the “p” in Slope. It is Ali’s voice that reaches me most deeply. We were born the same year, and seemed to move in tandem through the milestones of adulthood — career and commitment, marriage and motherhood. When we first met in the late ’90s, both of us were dating bearded sardonic Jewish men with receding hair lines and razor sharp minds; I, her brother Jeremy; Ali, the man who would become her husband, David.

As a foursome, and later with our children, we spent many hours together at my in-laws’ beach house, chortling over own cleverness as we snacked on malt-dusted ice cream drizzled with chocolate syrup. There were arguments, too, usually petty, and sometimes explosive. After she was diagnosed, though, the conflicts diminished. Ali deeply appreciated the love around her, and carried herself with dignity to the bitter end.

I often think of a conversation last January at the Menorah Hospice in Manhattan Beach, where Ali spent her final weeks surrounded by singing friends, decadent food and enough flowers to populate a suburban garden. Ali’s face lit up with joy as she sampled the pungent cheese she had assigned me to bring that morning.

We spoke of the party that had taken place the previous weekend. “Nobody has friends like you do,” I told her.

“Am I lucky or am I unlucky?” she pondered. She smiled, then turned tearful, then cheerful again. “I have amazing friends, a loving family, a wonderful spouse, incredible children. And also this,” she said. She glanced toward the large windows behind us, her hand sweeping across the view of the deep blue Atlantic and sunny skies.