Sansa unfortunately has no real choice but to go through with her marriage to Ramsay Bolton, and its made worse by the fact he forces Theon to be the one who gives her away. The same Theon shes just repeatedly heard tell her how he murdered her brothers. That is just the tip of the iceberg though. Thats because, as they say in Westeros, after the wedding comes the bedding. While Sansa may have been a little prepared for the night, and expected the worse, it doesnt make what happens any easier. First of all Ramsay taunts her about her virginity, and then proceeds to rape her. If that wasnt enough, he forces Theon to look on as it happens. Looking past the controversy and outrage the scene has caused, and focusing instead on the rape within the context of Ramsays evil deeds, it may not be the worst thing he has done. But when you consider the act, and that its their wedding night, and everything else Sansa has had to endure, and the fact that this is just the beginning, its another extremely awful example of Ramsays complete and utter viciousness and lack of morality, and even humanity. Joffrey threatened to rape Sansa, but never acted upon it, and you imagine he probably couldnt anyway. Ramsay didnt threaten it, he just did it, and hell probably do worse. Thats the major difference between the two.