I think his manipulation to get Regina to shove her through the mirror was, for Rumple, a solution to a problem long past, as well as a spot of vengeance…which I think we’ll learn about in the next few episodes.
But we knew Cora couldn’t be trusted. For anything. And Rumple should’ve known, too, but Cora hit him right when she knew he was most vulnerable–after all, she had been helping Hook all the time and knew exactly what had happened with Belle, and knew just how important getting back to Bae had become (even if she didn’t know before, which she might have). She hit both Rumple and Regina at their most desperate, which we know was always her intention with Regina. Rumple was so off-kilter he even asked her about memory spells, in almost the same little desperate tone as he once asked Charming for dating advice. For Cora, Hook was just another tool to keep Rumple from being a threat to her while she pursued whatever ultimate plans she’s got. And we’ve seen her turn on Hook a few times, turn on Regina, turn on just about everyone who is foolish enough to think that they can deal with Cora and not get bit in the end by it.
Keeper of Belle's Gold magic, sand dollar, cloaks, purple FTL outfit, spell scroll, library key, copy of Romeo and Juliet, and cry-muffling pillow, Rumple's doll, overcoat, and strength, and The Timeline. My spreadsheet: https://drive.google.com/file/d/0B6r8CySCCWd9R0RUNm4xR3RhMEU/view?usp=sharing