Wiktionary
betrayingly
adv. In a way that betrays or reveals.
Usage examples of "betrayingly".
The neat, short-nailed, scrubbed hands that she had folded in front of her suddenly twitched betrayingly as Garth waited.
Her fingers trembled betrayingly as she reached for it, turning it face down as she rammed it into the nearly empty drawer and slammed it shut.
He kissed her slowly and lingeringly, bemusing her so thoroughly that she wasn't even aware of him gradually lowering her so that her feet could once more touch the floor, thus freeing his hands to cup her face and her arms to instinctively and betrayingly creep round his neck, her heart pounding suffocatingly, as his tongue tip stroked her trembling lips.