Responses
Is it this one?
http://www.mangago.me/read-manga/empress_of_another_world/?av=1
Is it this one?
http://www.mangago.me/read-manga/empress_of_another_world/?av=1
I am looking for the one where the girl fell down into a portal at a train station. The family made her pretend she was their daughter so she would be sent to the king to marry and when he was about to rape her the kings son killed him. She ended up working with the Kings son to get rid of his Mother-in-law. In the end they had two girls together and lived happily.