When the coronavirus hit, Cat Marnell was in Cairo.

“I was in a $15-a-night Airbnb. It was a penthouse with wires dangling down and no running water because of a flood. It was so dangerous,” Marnell, 37, tells The Post.

“Whenever I could get online, I would read what was going on with the coronavirus and realized I had to get back to the US,” adds the former magazine editor and reformed party girl.

The author of the memoir “How to Murder Your Life” — which details her high-flying, club-hopping ways and her struggles with addiction — skipped Cairo for Paris in mid-March as borders in Europe began to shut down. She then hopped on an empty flight to Newark at the end of the month. She was staying in an artist colony in a Troy, NY, church when the host was tipped off that she had traveled from Europe, which was at its COVID-19 peak. “I was asked to leave,” she says.

After a two-week stint in an Airbnb in Bushwick, Marnell has since decamped to New Jersey to live with her sister, publicist Emily Marnell-Stewart, her husband Jack, and their children Lila, 4, and Charlie, 2. She’s also been mourning her friend SAME, an NYC graffiti artist who died last month. He, Marnell adds, “would want New York to get weird again.”

She thinks this summer is the perfect time to move back to her old stomping grounds: Manhattan.

“I feel obliged to in this time of weirdness,” says Marnell, who adds that though she has been on the road for the past two and half years — with adventurous stops in 73 countries — she’s signed a lease in the East Village starting June 1. “I got a really good deal on an apartment —  $2,500 with a kitchen and roof access.”

Here’s what she’s been doing while biding her time in Montclair, NJ.

What have you been working on in lockdown?

Let’s be honest, my career is all I’ve got. I’m writing my second book now, and I’m trying to write as much of it up front as I can before I sell it. I used to be that person who wasn’t reliable, so now I want to prove myself first to people.

I’ve also been working with producers at Sony TriStar and we’re pretty far into the development for a limited TV series from my book. The star is attached, and she’s the funniest and best person. Now we’re looking for a showrunner and director. Of course everything’s been a bit derailed but I’m still doing Zoom meetings.

Plus, I’m the special correspondent on the Cookies Hoops basketball podcast, which I listen to all the time. I covered the NBA Paris and Mexico City games for them. I report back what I see and the gossip I pick up and generally give the show some girl energy. I’ve upgraded my tech, too, so I’ll be on their podcast more regularly.

What have you been watching?

I’ve been watching Leah McSweeney on “Real Housewives of New York City.” She’s my old friend, we had a 30th birthday party together, plus my sister is her p.r. rep, too. She’s the best thing happening right now.

Of course I watched the Michael Jordan series, “The Last Dance.” Besides workout videos on YouTube — I love JJ Dancer’s videos and PopSugar Fitness — I only watch NBA clips. The NBA is very important to me: I think it’s magical, inspiring and uplifting. I’m deeply upset it’s gone away. But I hear the Eastern Conference might be at Disney World.

Any quarantine purchases?

I consider my main job as an aunt is to bring things into my niece and nephew’s lives that their mom might not allow. If my sister says they have too many stuffed animals, then Aunti Cat — which I like to spell “Anti,” like the Rihanna album — orders them huge stuffed animals. My sister gave me free rein of her Amazon account.

I recently ordered Lila a 65-piece plastic jewelry set. It’s beautiful. I’ve gotten her a full, really uncomfortable, impractical “Little Mermaid” bathing suit with an all-out tail. I got her a garment rack to put her gowns on, knee-high Elsa boots and feather boas. I’m her glamour tutor. We’ve been doing French lessons together, too, and watching “Frozen” in French.

I didn’t want my nephew to feel left out so I got him a pirate chest and jewels to fill the chest. I got him a circus tent with blow-up clowns and a full king’s outfit — robe, a crown and a scepter with a jewel on it.

Have you been taking up any hobbies?

Besides practicing French with my niece, we also build a lot of fairy houses. They’re easy. Fairies are like me: They only need a place to sleep for one night, they’re always tired. They’re like little hobos with wings.

I’m thinking about making a dress stuffed with glitter and colored powder in the hem. Then you could puncture it, and when you walk, you leave a trail of pixie dust made of glow-in-the-dark powder which I’ve been buying in bulk on eBay. If anyone sees any streaks of luminescence downtown on Avenue C this summer, that was probably me.

What have you been wearing?

I wear a black-on-black Yankees cap that I bought at the Istanbul airport. I’m always in exercise clothes. I’ve been in Adidas leggings and a Nike sports bra. My sister has been letting me wear her clothes, too, because I only have what I traveled with.

I’m so excited to get into my storage unit. I need my dresses and my gowns. And my shiny Jeremy Scott jacket with the wings and the fringe that came out a couple of years ago. I have a lot of glow-in-the-dark clothes, too.

I’m trying to invent something where you turn a bed sheet into a gown, like staple it to yourself. That’s going to be my look this summer, a bed sheet gown and to be wrapped in LED lights with a battery pack. I’ll wear that and I just ordered a Cheshire Cat cup with a straw from the Disney Store. So I’ll be drinking my spritzers — Kendall-Jackson white wine, which I discovered on Amtrak, mixed with Perrier on ice — out of that.

Of course I’ll have my mask. All of mine have lipstick on them currently. I saw that the Disney Store is uploading some, so I got on the wait list for those.

Any plans for when you get back to the city?

I plan on spending the summer under the FDR, which is the best place in New York anyway. It will be my nightclub, my bar, my office. All I need is a bench under the FDR between the Brooklyn and Manhattan Bridges.

My main restaurant when I lived in the city was the 7-Eleven on Lafayette just below Canal. And also 7-Eleven on the Bowery, and the one on Broadway downtown, so I’m excited to get back to those. I get the dried pineapple there. And the pizza, which disgusts people, but it’s made fresh!

I also love Frank Prisinzano’s restaurants, like Lil’ Frankie’s and Frank. I love the baby meatball pasta or the pizza from Frank, and that salad with the Gorgonzola and pears. If I’m going to get dessert, I’ll get the tiramisu.

I’m excited to see my best friend Shaun Crawford, who’s a graffiti writer who’s collabed with Supreme, and now he does home goods. He just sold a devil rug that he designed to Drake at the Dover Street Market in London, but he wasn’t credited in that Architectural Digest spread of Drake’s house.

What have you been eating?

I eat every meal with the kids, which is fine, because I eat child portions anyway. I eat toast with peanut butter, and fruit smoothies for breakfast. I eat a veggie burger and a salad for lunch, and whatever my sister orders me for dinner. I eat an apple with almond butter every day because I heard LeBron James does that.