Any repetitive, intrusive thoughts of harming someone should be reported to a psychiatric healthcare provider, if you are not seeing one already, as soon as possible. Obsessive/compulsives often act upon a ritual to relieve anxiety, such as compulsive hand washing, repeatedly checking an already locked door, placing things in a certain order and then rechecking that order many times. The acts are harmless in themselves, but cause a great deal of discomfort and can consume much of the individual sufferer's time. Now harming someone with an automobile or any other manner is a very different story altogether. If you act upon this compulsion, it is criminal and you will be held liable to the full extent of the law. You should seek immediate psychiatric help. Those are more darker and potentially dangerous OCD thoughts and you should be forthcoming with loved ones about this. You should have said something when you were in for surgery, you could have seen the resident psychiatrist and you probably wouldn't be posting a scary comment like this now, because he/she would have been able to help you. Please take care