Is it normal i dream of killing my ex's new girlfriend.

My ex and I have been together for four on and off years. We finally split for good (so we say) and his new girlfriend is someone I have been enemies with for over a year. I dream of killing her different ways every night. He is treating her like the Queen he use to treat me and. I guess I am jealous. I rather dream about killing her than actually committing the murder but is this normal? Is this just my emotions getting the best of me as I sleep? Should I be afraid? Also I always wake up like right before I finish the job, do you think if I sleep all the way through and finish the job this problem will go away?