Marriage Alliance for Revenge is a Manga/Manhwa/Manhua in english language, Drama series, english chapters have been translated and you can read them here. You are reading chapters on www.mgeko.cc fastest updating comic site. The Summary is

Olivia, the Empress of Rhone Empire, died because of her husband’s scheme, then she had a chance to live again in the body of an unknown woman who lived in a slum. After that, Olivia met her ex-fiance, who was the real heir to the throne, and hid her real identity from him. She made a suggestion to form a marriage alliance for each other’s revenge. Will their revenge succeed without any obstacle