My thoughts are just like yours, to the point that I could have written your post for you, right down to a bad panic attack in January 2013, which kicked off the worst year of my life. The constant thoughts of harming myself/others, becoming some deranged lunatic. Becoming something truly evil. I have struggled with the thoughts everyday for the past several months. It seems like even when I'm able to tell myself that I am not a violent person, I immediately start to worry that I will become a violent person. I fear that I will lose sight of my moral code, lose sense of myself and I fear that I will start to enjoy the ideas. I begin to feel unreal like I'm not in my own body. Then on the days where it seems like I'm not as anxious about the thoughts, that scares me even more! and so the cycle starts all over again.
It's a rough road, I know. Are you taking any meds? or better yet, still seeing a therapist? These things have been helpful to me so far. I've been taking Celexa for about 2 months now, and seeing a therapist for about a month. The meds take the edge off of the fear and weekly therapy has helped me gain some insight and perspective. I'm not "cured" yet, but I can say that I am without a doubt better than a month ago. I can be around scissors without feeling a jolt of terror, for instance. It's a process.
Have you been able to talk about this with any close friends or family? In my experience, I have found that my family has been extremely supportive and even the closer friends I have told have been extremely supportive. It helps to have someone to talk to. Pain shared is pain divided!
Hang in there! We share this form of anxiety with a LOT of other people. It sometimes seems like we are alone, but it is not the truth. This is far more common than most people realize. We are not our thoughts, and those of us who suffer from these intrusive thoughts are not violent by nature. That's why it causes us to feel this way.
I wish you the best of luck!