(Photo: Nina Andersson)

One Sunday last spring, I went to Harmony Playground in Park Slope with my family. The sun was shining, all the families had just gotten back from their Easter vacations, and the dads were pushing their kids on the swings, exhausted from a long weekend of full-time child care.

Jake was sitting on the jungle gym with our 9-month-old daughter, Alice, who was holding onto the metal guard bars and panting with excitement. I was feeling exuberant and maternal, enjoying how much fun Alice was getting to be now that she was close to walking. I glanced around happily when suddenly my stomach lodged in my mouth.

Sitting on the edge of the sandbox, next to her very bald husband, was my EBF, or ex–best friend. I had used this acronym for years, and all the single girls I knew had one. Whenever I told my breakup story, I’d get a nod of understanding and a confession: “I’m still hung up about mine eleven years later” or “I can’t talk about mine without crying.”

I’d had a falling-out with my EBF almost five years ago for a litany of reasons, some spoken, others unspoken. And yes, one reason involved a guy. She had been treating me horribly for a long time, but my ego couldn’t handle her rejection and almost a year after we stopped speaking I wrote her a long e-mail pleading to reconcile. She responded that she was very sorry but in truth she had never considered me her best friend anyway. This is why you don’t contact ex-friends.

After I got pregnant, I began to see the acronym EBF on mothering message boards. I didn’t understand why so many mothers were obsessing about ex–best friends until I realized that it stood for something else entirely: exclusively breast–feeding. “I’m EBF,” a mother would post, “and I’m worried about my milk supply” or “If you’re EBF-ing, do you still have to use birth control?”

I glanced over at my EBF. Her back was to me, but her back looked happy. She was talking to her brother, who lived in my neighborhood, and watching her toddler-nephew play in the sandbox. “Oh, God,” I said to Jake. “It’s my EBF. Quick, tell me. Does she look ugly?”

“I don’t even know where she is,” he said.

“Sandbox. Three o’clock.”

He wouldn’t turn. “Why are you even thinking about her?” he said. “You’re here with your husband and beautiful daughter.”

“I can’t help it,” I said. “She totally traumatized me. She dumped me.”

“So what? She’s a bitch,” he said. Men have a way of saying bitch that can totally brighten your day.

I craned my neck to see if she had gotten fat, or old, but her sturdy husband was blocking her entirely. She was a blank slate. And so I went to the darkest place.

I felt like I had nothing in life, as if she, not I, was the fulfilled mother in the playground with her hot husband and cute daughter and I was a spinster thirtysomething, trudging a walk of shame. I wondered whether she was pregnant and if that was why she was in a playground hanging with her nephew. And if she was, was she having an easy time of it? Or was she a mother already, watching her own toddler in the sandbox? Had she had a horrible labor? Was she about to? If she knew that I hadn’t been able to do natural childbirth, would she think less of me? Would she get an epidural? Would she tear?

And even if she wasn’t a mom, was her marriage better than mine? If she didn’t have a kid, it had to be better. Were they living out the newlywed honeymoon I had for only a year because I got knocked up? Was she happy in a real way, or was that carefree, sunny face a cover? Did she and her husband fight? Did he ever storm out the front door, so incensed he couldn’t even stay in the apartment? Did she have lots of friends who were there for her, or did she sometimes wish she had more? Did she ever look back on things with me and miss how funny I was? Had I really never been her best friend, or was that something she said just to hurt my feelings?

I grabbed Alice and raced to a nearby bench. “What are you doing?” Jake asked.

“EBF-ing,” I said, unclipping my nursing bra. My daughter is a really adaptable baby, and within seconds she had happily latched on.

“Are you sure she’s hungry?” Jake said, sitting down next to me.