It takes her a week, after she's made her decision, to actually do it.
First she has to make her arrangements; an appointment (and then another after she "forgets" the first one) with a place in the nexus that does tattoo removal, setting up a new account ("Donnatella McKay") with the NMB and shifting some funds around, rechecking a few things she'd been working on for the kids...
When it's time (finally time, she can't breathe, she can't breathe, she doesn't know if it's this house or the knowledge that she's steps away from being free again that's suffocating her), she waits until everyone's asleep before taking out the suitcases she packed previously and calling a cab for an hour's time.
Jonathan and Elizabeth have proved, time and again, to be perfectly capable of taking care of the children. They'll help John, and his alternate might be persuaded to give a damn about the rest of the family if Elizabeth tries hard enough. Donna's not blind to the fact Nami's been intercepting people on their way to her; it makes her ache, a little, that she's let herself get so ragged that someone she's supposed to be responsible for is taking responsibility for her.
It's like she's reliving the worst mistakes she made after she left John -- but she knows better, now. It's probably another mistake to leave, instead of trying harder, but Donna's tried and tried and she's in over her head. Let them all call her everything they want to -- they're probably not wrong, but she's almost beyond caring.
She kisses Gilly and Robert goodbye, leans in the doorway of her bedroom with Robert in her arms and watches Jonathan sleep. Her suitcases are by the front door, and she's dressed smartly in her 'traveling suit' and coat and respectable heels.
Nami is standing at the end of the hallway, between Donna and the stairs, when she turns around. There's a long silence between them, and then the teenager holds her arms out for Robert. Donna hands him over and kisses Nami's forehead.
"You're really leaving."
"Get some sleep, honey."
She can feel Nami's eyes on her even long after she's out of her sight.
J, J, E-
Don't follow me.
- D.