I need to get an abortion because baby is abnormal. How can I justify this?

Very justifiable. You don't want a baby to be born with defects-physical /mental delay . Giving birth to them and making them to pull through life , with all the difficulties is like almost like tormenting the child to be born into the world knowingly. Instead though it is very painful to abort the child you conceived with great expectations you avoid the mental and emotional trauma to the child as well as you.