Actually, I Had A Sex With My Wife 15 Days

Actually, I had a sex with my wife 15 days before, and now she is saying that she is pregnant, we did check it wit pregnancy kit, which showed the result positive, now I want to abort this child as I already have two children, without informing the elder member of the family. I know that a mistake has been committed but not want to repeat it again.. Plse guide what abortive pill will be the best to abort a 15 days old child.....