OP, please get some therapy as soon as possible. Start the process right now- start looking for resources online, research all the therapists and psychiatrists in your area, figure out which of them have timings and slots and offices which are convenient for you- get on it sooner rather than later.

Your thoughts and desires do not make you a horrible person- but your actions do. Which is why you need to be pro-active about this, and figure out how to live a happy and productive life without ever acting on your thoughts.

While it can be very difficult, you already seem to have your head straight and your heart in the right place- what you need to do now is learn some techniques to deal with these intrusive thoughts and have someone trustworthy (a therapist) to hold you accountable.