This. Everyone applaud this.
As for me and her majesty Chrysalis, I think she wasn't doing it for strictly evil reasons. Yes, attempting to take over Canterlot, pwning the ruling power, and kinapping a bride to be is pretty evil. But consider this: what if this was an act of desperation?
Warning: Poorly Thought-out Head Canon: Changelings live in a harsh environment far from other living things (according to the comics... I think... I don't know for sure, I only skimmed through one). Perhaps this was a low point for the Changelings. Running out of food and other infiltration attempts failing, Queen Chrisalis is forced to enact a desperate plan to bring a food source to her starving children. She hears about a royal wedding, and for the Princess of Love, no less. Her fiancé, a mere mortal unicorn, would undoubtedly feel unending love for her. As the only female changeling (as far as I am aware, though twitter argues different), she faces a handicap her unisex children do not; gender specific transformations. She can become any living thing she desires, as long as it's female. So manipulating the Princess was out. But her fiancé was male, and a mortal. Much more susceptible to mind control than his lover. So she would use him, slowly take control of his mind, and when the wedding was complete, she would reveal herself. Using her new husband as a puppet, she would bring her innumeral children down upon the city. She would capture any and all who were together, as husband and wife or as special someponies, and absorb their love en masse. To a queen blinded by the needs of her children and with almost no other place to turn, I think this would seem plausible. This would explain some of her gaps in logic when it came to her plan.