It means "Do you really think that I hate you(a king)? If I translate it in detail for you to understand the nuance, it is like "You cannot say that I hate you! It doesn't make sense! How can you think like that?"
If you use "설마" in a sentence, it is like you are saying something with doubt.
*Actually there is a typo in the Korean sentence. It should be "설마 내가 전하를 싫어 하리이까?"