Will my sin be forgiven after I got rid of my sister's newborn, who was conceived as a result of rape, out of fear for her life, knowing that my conscience is tormenting me for what I did?

The questioner must repent to Allah, seek forgiveness, and perform many good deeds for throwing the infant in the trash. If she believes it is highly probable that the infant survived, then nothing is required of her after repenting and seeking forgiveness from the infant's sister (the infant's mother). However, if she believes it is highly probable that the infant died due to being thrown, then she must pay the diyah (blood money) – one hundred camels for a male and half of that for a female – to the infant's heirs, in addition to the kaffarah (expiation), which is freeing a slave. If a slave is not available, then she must fast for two consecutive months.