The World Without My Sister Who Everyone Loved is a Manga/Manhwa/Manhua in english language, REINCARNATION 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

“I hate you enough to want to kill you, Sienna.” I was my sister’s shadow all my life, and I was betrayed by her and died. But… people have changed since the day I came back in time. “You’re the only child Nacht chose.” “Your Highness recognizes you as family.” Something’s wrong. These people seem to mistake me for my older sister. “I beg you, believe in us for once, that we care for you.” I once wanted to be loved. Now I fear that this mindset will become my weakness. One betrayal was enough. Everything is over when you bet everything in love. I just want to get my life back so…