“What’s it like to have lost your father?” the social worker at Mount Sinai Medical Center asked me at our second visit to the hospital’s Wien Center for Alzheimer’s Disease & Memory Disorders.

“What are you talking about?” I thought to myself. “I haven’t lost my father. He’s just outside, in the hallway, waiting for me.”

She went on to tell me what would happen over the next few years — how he’d be unable to groom himself, probably lose his mobility and even his ability to speak, and need round-the-clock care.

My father? The man who never came out of the bathroom without a splash of Old Spice, who in his mid-80s still had a strong right arm that he used to toss tennis balls at the dog park, who got up an hour before dawn so he could swap stories at the golf course with the first guys to tee off.

My mother had suspected he had Alzheimer’s for some time. But for many years, Mom and Dad were able to compensate for one another. My mother, whose mind was sharp, had trouble with her legs. She could walk, but needed an arm for support. My father, who couldn’t formulate an answer to a question, was physically strong.

After a particularly bad fall when her ankle was shattered, Mom was in the hospital after surgery. Dad would spend the day in the room with her, just sitting in a chair, looking off vacantly and not saying a word. In those last weeks, I was with my mother nearly round-the-clock. During one of those late-night, early-hour conversations, she tried to prepare me for my future.

“I think your father has Alzheimer’s,” Mom said.

“Yes, I agree,” I said. “Once we get you out of here, we’ll take him to the doctor.”

“I’m sorry to leave you with him,” she said.

A few days later, she was gone, taken by pneumonia.

Mom had been Dad’s everything — the one who guided him professionally, the one to fix his meals, pick out his suits and ties, keep a perfect home, put money aside for a comfortable retirement, and even let him hit as many mulligans as he liked on the golf course.

He had never in his life paid a bill, gone grocery shopping, tidied the house, done laundry, fixed a sandwich.

On his own for just three months, Dad quickly dropped from the 140 he’d been his entire life to 120 pounds. Also diagnosed with Parkinson’s, he became more wobbly and frail. The man who was always smiling and whistling a tune now cried continually.

Always a stellar athlete, Dad played in the baseball minor leagues in the 1940s. He could have played any position. But a smart guy liked Joe Carr only wanted to catch — it was the catcher who really controlled the game, he said.

He was with a Yankees farm team when Lefty Gomez, the Hall of Fame pitcher and teammate to Babe Ruth, broke the news.

“Joe, you’ve got a really strong arm. And you’re a smart guy. You’re just too tiny. Some 200-pound third-baseman is going to slide into home plate and cream you.”

Dad packed away his catcher’s mitt for 30 years.

He only got it out when his non-athletic daughter — me — began playing softball. One day, the coach pulled me out of right field to pitch. The ump — my father — called a record 40 balls.