She never thought it would end like this.
Yes, she knew what they did was dangerous and they'd had close calls, but they'd always made it out and after a while it just seemed liked they always would. Maybe their luck had run out.
She goes over her actions in her mind, what brought her here, she's got time now, time to kill. Ugh, she thinks shaking her head, why does her brain always come up with the worst way to say things?
It's simple really, she let her guard down. It was the price she paid, she supposed, for a year of happiness. Because things had been good, so good, perfect, for long enough that she let her diligence slip, just enough it seemed, to get her here. But she can't bring herself to regret it, and despite her situation she smiles. Even if it all ends now, it was worth it; her life with Oliver was worth it, she wouldn't change a day. So she makes a choice. Instead of living her last moments in fear, she focuses on him. She thinks about his smile, the one he saves just for her, that never ceases to make her heart flutter. She thinks about the sound of his voice, deep and smooth, as he says her name, as he whispers 'I love you'. But most of all, she thinks about how wonderful it is to be loved by him, to have his whole amazing heart and soul. The warmth that washes over her with these thoughts pushes away the panic that was clawing at her chest and, as her mind starts to drift away, it's almost peaceful.
Felicity always knew she'd love Oliver until the day she died. She just didn't realize that day would happen so soon.