Help Me Find a Manhua.

Basically, the female lead either gets kidnapped or transmigrated into this Western-style fantasy world where she is then forced to pretend to be the prince's deceased lover or something. The love rival, maybe the prince's fiancée, I can't really remember, is mean to the female lead, but it's actually because she wants to protect her as her family kills anyone who is close to the prince to ensure that the love rival gets to marry the prince. The female lead was fighting someone and gets decapitated but turns out she is vampire or creature or some sorts that gets stronger after being decapitated or something.