She might set his hair on fire. Or hit him with a frying pan. Or just shoot him. She still had her gun. But Killian might get more mad at her for maiming his lover, possibly just as much as tethering him to an evil magic.
"Unless I get mad at you and kill you. Then I'll just feel worse and you'll be recycled through this place. Then we'll be worse of than we are." Then again, maybe her magic wouldn't be the same as it was now, maybe her heart was darkened by the magic and her savior magic would suffer. That was the point wasn't it, she was pure love, the product of True Love, made all good by her parents putting her potential for darkness in Lily.
Maybe she was broken now.
"I'm not practising magic here. Wouldn't want another tantrum, would we."