Everyone has the right to form and share their opinions about various forms of media, be it books, movies, or music. It's a natural part of engagement, and sometimes these opinions can be unpleasant or even harsh. It's important to recognize that not everyone will agree with you, and that criticism can come in many forms, often from people who may seem rude or unpleasant.
However, responding to negativity with harassment or hostility only reflects poorly on you. Whether the dissenters are behaving badly or not, taking it upon yourself to issue threats or become a nuisance makes you part of the problem. Ultimately, you are only accountable for your own actions and should focus on your own life rather than retaliating against others.