Nothing should be in your writing unless it serves the larger story. It doesn't matter how cool a concept or a character is, if it isn't creating the experience you want for your reader, out it goes.
I think you've answered your own question in a certain way. If your aim is to show how distressing this character is --within the story! --then show that through his impact on the people around him. The things that are often most disturbing in fiction are the things kept mostly offstage, so that the audience uses their own imagination. Instead, you can build up this character's horrifying reputation among the other characters, and just give little glimpses to the readers. Write the full scene, if you must, but keep it as backstory. It doesn't have to go on the final page. (Going full-out isn't just disturbing, it also runs the risk of tipping the balance and becoming unintentionally laughable.)
If you, the writer, just want to indulge in a gratuitous bloodbath, AND force the reader through it, that's your right, but you may lose most of your audience. Or not --Game of Thrones is notoriously brutal, and while I could personally never stomach it, it certainly didn't lack for fans.