I've no more business to marry Edgar Linton than I have to be in heaven and if the wicked man in there had not brought Heathcliff so low I shouldn't have thought of it. It would degrade me to marry Heathcliff now so he shall never know how I love him and that not because he's handsome Nelly but because he's more myself than I am. Whatever our souls are made of his and mine are the same and Linton's is as different as a moonbeam from lightning or frost from fire.
"I've no more business to marry Edgar Linton than I have to be in heaven," reflects the narrator's strong feelings of unworthiness and internal conflict about her marriage. She feels that her love for Heathcliff is genuine and deep, but societal expectations and personal shame prevent her from acting on these feelings.
She describes her love for Heathcliff as rooted in a shared essence, feeling more connected to him than to anyone else, including Linton. She emphasizes that her love isn't based on superficial qualities like appearance but on a profound spiritual bond that defines her true self.