As E.B. White said, “It’s not often that someone comes along who is a true friend and a good writer.” Sue Grafton was the big sister I never had: encouraging when I needed courage, honest when I needed truth, and funny.

We met in Columbus, Ohio, in 1981. I was 24 and writing for magazines; she was 40 and writing for film and TV. I read that she was giving a talk, so I looked up her number and called. Days later, we were meeting every morning to run laps around Schiller Park.

Sue told me she’d just finished a novel and handed me a box with a stack of typewritten pages. The title? A Is for Alibi. She knew my dream was to write a novel, too.

When I moved away, we began trading letters every two weeks. Sue called them “wall-to-walls”—sheets of paper full of words, no margins. Hers often ended: “Love, love, love, love, love!” After Sue died, I found the trove and started rereading.

She’d found a new jogging partner and wrote, “I’m always talking about Carol this and Carol that. I miss you so much!” and “I gnaw my nails over B.... Some days I think it’s fine and other days I think it’s shit.”

My dad died, and Sue wrote, “I always feel that it is a compliment to grieve deeply.” In 1983, she got a word processor, a Fortune 32:16, and opined: “Looks like NASA Ground control in our office now.”

Harper & Row bought my first book, Girltalk: All the Stuff Your Sister Never Told You. “I can just picture you and Rob dancing around the house like nuts,” Sue wrote. “Truly, life doesn’t present us with that many moments to celebrate and it’s nice to go all out when they come. I’m really proud of you and I won’t tell a soul that you’re not really as humble and loveable and modest as you pretend to be. Don’t tell on me either.”

In 1985, Sue came to Manhattan to attend the Edgar Awards. She and her husband Steve slept on our sofa. (Twenty-four years later, she would be named a grand master at the Edgars.) Before fame and fortune, Sue even cat-sat for us. “Chanda slept on my neck, my shoulder, in my armpit, on my face,” she wrote. Two paragraphs later: “Can you believe I’m writing you half a page on the feeding of your cat?”

Sue taught me that “hand-wringing” is part of the writing process; that two-millimeter calligraphy pens are ideal for signings; that, if you position yourself in the middle of a group photo, no one can cut you out. And that you need backbone: she and Steve teased me for having baked cookies for my editor; they informed her editor that Holt had better get behind E Is for Evidence because it was going to be a bestseller. (Holt did. It was.)

Soon emails replaced letters, and Sue and I phoned on birthdays.

When I was 42, Knopf bought my first novel, The Diary of Melanie Martin, and I called Sue before I called my mom. In 2013, after a long, painful rut, my new agent sold Ava and Pip. Sue wrote, “You are da bomb!... What agonies you’ve been through!... Go get ’em, champ! I am sooo proud of you!!!” She posted on Facebook: “GRANDPARENT ALERT... My grandkids love the Ava Wren series.... If the author doesn’t continue the series, I’ll extract my revenge in blood.” (My Amazon numbers spiked.)

On December 14, I emailed about the wildfires near Montecito, Calif., where she lived. She replied: “Our house is still on mandatory evacuation. Wish us luck!”

My last words to her: “Luck Luck Luck Luck Luck Luck!!!!!!”

Two weeks and one day later, she passed away. I called Steve. “It’s so weird,” I sobbed. “It’s taking over Twitter! The whole world loved Sue. But not like we did.”

Carol Weston is the author of 16 books; the latest is Speed of Life (Sourcebooks Jabberwocky, 2017).