what do you think of this theory i just thought of for the episode after the winter break?

i was just thinking, when hook and cora arrive at storybrooke, cora tells hook to wait here for rumple and that she's gonna go find her daughter. when she finally does, she gets into a small argument with her which ends with regina about to lunge at her but then cora sticks her hand into regina's chest threatening to take her heart out unless she cooperates. cora convinces regina to think twice about redeeming herself and tells her that in order for henry to be hers, she must finish off emma snow and charming. regina is relucant at first but when cora again threatens to take out her heart, regina sadly accepts. then later on, regina comes by the school and convinces henry to come with her to her house and stay with her for a little while. because he still believes that she's doing better, he accepts and sometime after she brings him to the house, thats when she confronts snow david and emma when they come by her house asking for henry. thats when regina snaps and when she is shown using her magic to push emma. i still wanna believe that emma is really cora in that scene but i just thought i'd share another possible theory. feel free to share your thoughts.