This is merely my take on what went through Regina's head when Robin and Marian were reunited. It is based on her initial reaction and does not necessarily reflect the way she might feel after processing the events.
I own nothing but my words. Enjoy!
He pulls her into a tight embrace, their tiny son between them, and for a moment — just a moment — you are confused. What is happening? Understanding awakens and a pickaxe swings at your heart, gouging out chunks of your newfound wholeness. She is his wife and she is alive. She was dead, but now she's not. And your happy ending, the one you've been holding tightly, yet tentatively, is crumbling in your arms, breaking into smaller and smaller pieces, until there is only sand slipping through your fingers like a thousand crushed hearts did when you were someone else.
How could this be happening? You avert your gaze from the Hood reunion and it lands on her. Emma Swan. She stands before you with eyebrows raised and lips parted, her shock etched into every feature. She brought Marian back and you cannot believe she is responsible for the destruction of your second chance. You cannot believe that this woman, the other mother of your son, has driven a knife into your gut when you had finally, finally established some semblance of trust and perhaps even friendship. You cannot believe that within five seconds the delicate bond you've allowed to develop has unraveled — a bond that found its origins in a fierce and competitive hatred.
"You did this?" you ask, the disbelief lacing each word. You look at Emma and you know she has long blonde hair and emerald eyes, but all you can see are brown locks and pale skin and Emma has become Snow White before you. Because really, they are one and the same; they both betray you with their selfish, thoughtless actions that only ever seem to result in consequences for you.
And it hurts, hurts, hurts, as though your resilient heart is imploding, and the ache is all encompassing. You want to curl in on yourself and disappear from this nightmare, because this pain is a monster with a gaping crater for a mouth and it's swallowing you whole. Your eyes have become dams, holding back the rush of waters that push against walls, fighting to escape in torrents that will course down your cheeks in waves. You will not free the tears though — not here. Not with Emma Swan staring at you, mouth agape, excuses already in her throat.
You tell Emma that she is just like her mother — never thinking of consequences. Because it is true and their ignorance has cost you dearly. Twice. Your voice wavers and your eyes are full and shining, but you. Will. Not. Cry. So you reach down into your deepest cavern, seeking the embers of a fury that was once red and raw — seeking solace from the fiery anger that once made you feel alive when nothing else could. And you find it there, the smallest light, and you breathe on it and make it grow, because you need it to outweigh the hurt right now. And when you speak again, your voice is low and dangerous, reminiscent of a woman clad in darkness, who once ruled a kingdom with terror. "You just better hope to hell you didn't bring anything else back," you say to the blonde and then you turn around and walk out of the diner, refusing to look at Robin as you exit.
The dam breaks before you even reach the sidewalk and there are rivers running down your face, falling from your chin in fat droplets. You can already hear footsteps behind you and you just want to be alone, so you disappear in a cloud of purple smoke and reappear in your lavish bedroom. You feel the mattress pushing into the backs of your knees and you sink into it, as the last remnants of anger float back into the cavern, extinguished. And you sigh, even as the tears continue to fall, because you can't help but wonder if this is what those people felt back in the Enchanted Forest, when you squeezed their hearts into dust. Did it hurt like this? There is a moment of guilt, but you cannot dwell on that now, because there is only so much a heart can withstand — even the most resilient heart.
You think about Robin and Roland and the way they had already come to feel like home. Sobs are birthed from your aching chest and they rip through your throat, clawing their way out into the air, and everything is a paradox of being too much and not enough and that tension is more than you can take. So you curl up on your impeccably made bed and let the rivers soak your pillow. Your shoulders shake with the heaviness of your disappointment, as though they're trying to dislodge it, but it has burrowed beneath your skin and fused with your breaking heart. It is part of you now. And your sense of hope is a candle, burning low and flickering and threatening to dissipate altogether.
You wonder how it can hurt this much, because you know it hasn't been long, but you had jumped in with both feet and a vulnerable heart and you felt so much so fast. And you know that Emma's betrayal is part of the hurt too, and you can't stand the way you've come to rely on her as a trustworthy ally, because now it seems that your trust has been misguided and you are paying for that.
In time, the sobs begin to dwindle and you are tired, so tired. You are exhausted on every level possible and your stinging eyes finally drift closed. Perhaps in sleep you can find some reprieve, however temporary it may be. Perhaps you can rest there, blissfully unconscious, just for a while.