GEM's Manga

Orphan in modern day, she reads a book and ends up in this alternative world where her father is supposed to kill her when she hits 16 because she looks like her mother that chose the child over her own life and a new daughter turns up (cursed black magic child that was implanted in emperor's first lover by his "dead" brother-not dead and manipulating the sister who is doomed to cause badness after the book the girl read ended). Girl wins over her papa, avoids her new sister from moving in with them and finds out that she has some really strong magic that ends up drawing a very powerful mage to her side for a time to help her control her magic. When she needs him mist because she gets cursed by the sister.... He isn't there.

She was a noble that did everything right and was raised being told she was the next empresses by fates design. Her husband, the king, ends up falling in love with a woman who appears to have time-traveled from modern Japan. Tia ends up being forced to be the second wife, is accused of trying to kill the now 1st wife Tia was doing literally everything for (finances, running the kingdom, etc), is knocked over and miscarriages because of the 1st wives miscarriage, is accused of causing a miscarriage of the 1st wife (most prob Tia's dad's men attacking 1st wife on her behalf) that causes his, his sons and her own death.

Present: Juean and Tia clash, it seems but Juean saves Tia by using her only wish. It was all Duke Zena but, Juean decided to get on his side to foil his plan thissl time. You see, the prince was being poisoned in the past. This continued after Tias execution for 4 years.
The prince was killed in a last ditch war attempt. Having just given birth to her daughter, Juean was stabbed through the heart by Duke Zena in the last life.