We’ve rehearsed this moment in our heads for months—or at least, I have—but now that it’s here, like with all the big life stuff, I find I’m unprepared. You’d think I’d be used to it after the year we’ve had. When my mom surrendered, which was prearranged with the marshal service well in advance, I still felt like grabbing her ankles and begging her not to go. Instead, I stood dry-eyed and joked that I’d already started hoarding all of the ice cream in Los Angeles for when she comes home.

Only later, once she was gone, did I cry.

My ability to hold it together felt like progress, though. A giant step toward adulthood. Like the other day, when I made my own dentist appointment. On the phone.

I guess sometimes we grow up, despite ourselves.

With this departure, though, the calculus is different. We’re all thrilled—celebrated it, in fact, all last spring, with another balloon arch and even a cake. This time, we’re watching a natural, earned progression, what is supposed to happen in the normal course of things. The built-in goodbye at the end of the childhood. That final wave and then the no looking back before independence.

Still. The tears come, so many I don’t even try to stop them. Instead, I busy myself with details. I double-check the luggage, make sure each piece has a tag with a label and a telephone number, in case it gets lost. I run upstairs and grab Crime and Punishment and slip it into a bag.

And then it’s time. No more stalling.

My dad, Hudson, Isla, and I stand awkwardly at the door. Mom should be here for this, but that goodbye was said already, on one of our prison visits. I tell myself stories to make her constant absence feel better—that she’s on a yoga retreat, or away filming; that she’ll be home soon. At least that latter one is likely true. Mr. Spence said he thought her sentence of fourteen months, of which she’s already served six, will likely be reduced to eight on the grounds of good behavior.

Two more months is nothing. A summer of sleepaway camp. As she says, it’s just enough time to finish the memoir she’s been writing between her shifts in the laundry room.

A blink and she’ll be back.

But here’s the thing with this goodbye: This one is permanent.

Isla won’t be back, not for real. My sister and I will likely never live under the same roof again.