Sometimes I get these weird impulses to do "evil" shit. Like wishing one of my parents were dead or wanting to rape one of my women friends or whatever. Do horrible shit to people I really love. These thoughts are sudden, and as soon as I have them I reject them and feel ashamed.
Sometimes I masturbate while thinking about beating people to death, usually my ex-wife but sometimes random strangers. Those thoughts are "evil" too, but I indulge in them as extreme masturbation fantasy and never think about them when I'm not touching myself.
But it does worry me, like you say your thoughts worry you. I'm under the treatment of a psychiatrist, though. I also see a therapist on a semi-regular basis. Maybe you should consider seeing a therapist too? They won't call the police, trust me. I've said some pretty horrible shit to my therapist, stuff I'd never post even anonymously on the internet, and the partyvan hasn't come for me yet.
The drugs DO help, but even doped up on meds I still harbor violent thoughts and strange sexual fantasies. I'm just MUCH less likely to act on these impulses. It wasn't always so, which is why I have a bizarre criminal record.
tl;dr get help from professionals, not Anon